Thamul takes a step back and starts throwing weapons at Bandit 6:
First throwing a handaxe from his left side:

nat 1:/
And than throwing a 2nd one using the light property from his right:

To hit: 16 and 8 dmg with vex activated on my next attack.

Tanis quickly blocks the incoming attack with a well timed spell, and Warrick misses his strike with his quarterstaff. Thamul also misses his first attack on Bandit 6, but succeeds on hitting them with his second hand axe. They run round into combat range with him, and slice down at him with a scimitar. 

Bandit 6: 18 to hit with his Scimitar, 4 slashing damage on a hit. 

Selene then tries to finish the wounded Bandit off with a mind sliver. Bandit 6 DC 14 Intelligence Save: 5, 1 psychic damage on a failed save and - 4 from his next save. 

The bandit misses his attack, and is then bested by Selene's psychic assault. 

Zifni is up!

Initiative
Zifni: 22  <- CURRENT TURN
Bandit 4: 20 (-1 HP)
Tanis: 18 
Bandit 3: 18
Bandit 2: 16
Bandit 5: 16
Warrick: 13
Thamul: 6 
Selene: 5

"Thing about an ambush, always a two-edged sword," Tanis drawls conversationally at the bandit (2) he is facing.  "Steward Sten back in the Watch would set traps for the rats.  Even waited by rat holes with a rolling pin.  To ambush them, yeah?  But the rats got old Sten in the end.  Went and locked himself in the cellar on accident one night, and by the time we found him, the little buggers had chewed his flesh off down to the bone."

Switching his Hunter's Mark to Bandit 2, he stabs almost apologetically at his new foe's throat with his shortsword and then draws his scimitar for a backhand slice to try to finish the job.  If Bandit 2 is down, Tanis trots southwest to face Bandit 3.

Bonus Action:  Tanis switches the target of his Hunter's Mark from the (now-dead) Bandit 1 to Bandit 2.

Action:  Tanis attacks Bandit 2 with his shortsword.  He then draws and attacks with his scimitar, using the Nick weapon mastery of the latter to include the off-hand attack as part of the Attack action, against Bandit 2 if he is still up, or otherwise against Bandit 3 after moving to him.

Shortsword attack to hit Bandit 2:  25 (Nat. 20)
Shortsword attack plus Hunter's Mark CRIT damage on Bandit 2:  6 + 7 = 13 piercing
Vex Weapon Mastery:  advantage on next attack against same creature.

Scimitar attack to hit Bandit 2 (if still up) or Bandit 3:  16 (no Vex advantage against Bandit 3, but first roll was higher anyway)
Scimitar plus Hunter's Mark damage on Bandit 2 or only Scimitar damage on Bandit 3:  6 + 5 = 11 slashing (or only 6 slashing if against Bandit 3)
Nick Weapon Mastery:  off-hand attack can occur as part of the Attack action instead of requiring a bonus action.

Movement:  E - (attack, then assuming Bandit 2 is down) - S - S - S to face Bandit 3 (followed by second attack if first attack downed Bandit 2)

Free Action:  Tanis sheathes his scimitar to leave his off hand free so he can cast Shield as a reaction again if needed.

[Just realised as I properly looked at the battle so far that Tanis would have killed two of the bandits on his turn, so it's almost certain that the remaining two would have been killed in a round, if that, so I feel better cutting the battle short considering that it would have only lasted another round max]

After a decisive skirmish, the bandits are slain, their bodies scattered around the docks. The rain washes the blood off the cobbles towards the sea, and whilst you're not too injured, it seems that the ambush, or the killing of your opposition, doesn't sit right with Selene and Zifni. Quietly, they express their thoughts on how things have been going so far, saying that they're not keen to be caught off guard again, or have to kill as they have done tonight, so they choose to withdraw from the party to think things over and grapple with their doubts somewhere alone and safer. Perhaps they'll look to rejoin later, when the party's got a more stable footing in the skulduggery of the city and they'll be able to sleep a little easier, or perhaps not. Finding your way through Tempest City was never going to be easy. 

If you'd like, you can search the bodies and do whatever else here before planning your next moves. 

Warrick looks towards Tanis and Thamul, he certainly understood Selene and Zifni's opinion, he himself shared a similar one, but Warrick wasn't about to go back to being alone and scared. Safety was in numbers and Warrick needed friends he could rely on as he still didn't trust himself. It was going to take more then a close call or 4 to make Warrick rethink he was in the wrong crowd, though it was dwindling. "Well, the bodies may bring unwanted attention. We should do them the favor of treating them as they wished to treat us  perhaps they had some decent equipment if they had done this a few times and got some spoils. Then off the dock with some foot weights?" Warrick will start rummaging through the bandits closet to him. It felt wrong, but required, so he did it anyway. He nervous rubbed his biceps as he worked, do people put traps upon themselves for such an occasion? "Anybody recognize the tall gentleman wearing the luxurious purple rain cloak with a large gold chain set with rubies? Must be rather successful with that expensive necklace and medallions he wore. I couldn't really see his face, but i did catch that lock of light blonde hair hanging down the bridge of his nose. I like to know who are tryingto avoid,  makes it easier to do so. Plus he probably won't be too happy when his thugs don't show back up and he clearly got a good look at the likes of us."

OOC: just reiterated the stranger since it had been a bit since the original description 

Thamul agrees with Warrick "Yes let us check the bodies and make sure they are gone before anyone comes looking. Regarding the lead figure I have no clue who he was, but for sure we should be more prepared, and do some extra investigations before we go and track down rumours it seems."

After which he starts checking the bodies for any loot; he also retrieves the weapons he had thrown, and looks around for any hefty stuff the could attach to the bodies when dropping them in the water.

Investigation: 15
Perception: 10

"Well to bad people are leaving so quickly; But I, for one, would like to stay together. How about you all?" Thamul asks the others when they head back.

Tanis accepts the loss of Selene and Zifini with his usual gloomy stoicism.  "Dark Sister.  Cool Breeze.  You will be missed.  Provided we live to miss you."

He keeps watch while Thamul and Warrick loot and dispose of the bandits' bodies, wondering if in truth, they were any better than bandits themselves..

"Drow after all," Tanis mutters darkly.  "Best guess anyway.  Tall, slender.  I've heard dark elves can have pale hair.  Spoke mockingly of our attempts to thwart his deal.  These flunkies may be human, yet I think HE may not have been.  We'll see him again, I don't doubt, sure as sunset."

Rousing himself, he claps Thamul on the shoulder.  "Course we're staying together, Big Man.  At least I am.  Until there's no one to stay together with."

All the bandits have scimitars, light crossbows, and 10 bolts each, though they'll sell for far less than they're truly worth given that that the supply and demand of weapons in Tempest City is so high, you'd be able to buy blades for nearly nothing at any given market. In addition, each of them is wearing a set of leather armour, which would sell for a cheaper as well, however you notice that the suits are branded with a distinctive eye emblem on the chest, which likely represents the thieves guild the bandits belonged to. Given that they're supposedly notorious amongst Tempest City (despite you not knowing who they are), there's every chance a vendor might recognise the symbol when you try to sell to them, and whilst they're likely to still buy it off you, word might get back to the guild that you've been sighted selling off their dead men's loot. Other than that the bandits hold no more loot; seems they packed light for this ambush. 

Thamul is easily able to find some heavy chains and mooring anchors scattered around the docks that would do a great job at sinking the bandits if they were tied to their waists or ankles. 

Tanis scratches his chin.  "So... Doc keeps the bolts to use, we store the rest back at the Bleeding Rose, and sink the bodies off the docs?"

He rolls his shoulders and stretches, peering at the dark surroundings.  "Let's get moving.  Sooner we're back, the better.  Tonight's the night Snizgore's going to be waiting eagerly to welcome us home with a nice glass of warm milk and a bright smile.  I can just feel it."

Belatedly, Tanis casts (and continues to cast) Blade Ward on himself, though it is unlikely to do him any good with at least this fight being over.

Thamul makes sure the bodies are at bottom and is than ready to leave.

Warrick couldn't help but smile at his friends similar feeling about sticking together, then we're more equipped to manage on their own then himself so he was happy they agreed with the strength in numbers approach. "Bolts, bows, and scimitars. Might not be a big haul but better then completely empty handed, or in a similar predicament as this lot." Warrick dragged one of the bandits cover in their new weighted apparel over to the edge of the dock with one hand while holding a couple of the cross  ows in the other. "What would be more suspicious,  selling one or 2 pieces over time, or a bulk sale are accumulating a significant inventory? I suppose the slow slow sales over time draws less attention. We should return to our current accommodations and assess our strategy for electing where to offer our services."

(OOC: So is that 5 scimitars and light crossbows, plis 50 Bolts to add to inventory or should just assume to be sold at some  low price?)