Quote from TheStorywalker >>

If someone attacks a creature with this spell but they have multiattack, can they forgo the attack and attempt to attack the same creature again? By the looks of it you can, but this conflicts with the intent of the spell:

"Until the spell ends, any creature who targets the warded creature with an attack or a harmful spell must first make a Wisdom saving throw. On a failed save, the creature must choose a new target or lose the attack or spell."

I would say yes, they can. If they attempt the attack and fail the save, they have two choices: a) waste that attack, or b) use that attack against someone else. The only reason they would choose the former is if they aren't any other valid targets in range.

Either way, they can still try to attack the original target with their second attack if they want. They have to attempt a second Wisdom saving throw and go through the whole process again, which could result in the second attack being wasted as well. I don't think this is contrary to the intent of this spell, it's just part of the benefits of having multiple attacks per action.

So essentially, this is the ultimate solution to "escort the NPC" quests, or party favorites dying.

Not only that, but it can be used to protect familiars, or more importantly for paladins; mounts.

I imagine that with mounted combatant, light barding, and this, your horse will be rather difficult to target.

Situation: An attacker wishes to move up to a player with Sanctuary and use an Attack Action to hit him with an axe. The attacker gets two attacks per Attack Action. The attacker then plans to use a Bonus Action to cast Spiritual Weapon to again attack the defender with Sanctuary.

Question 1: If the Attacker makes his initial WIS SAVE against Sanctuary, does he get to make both attack rolls, or does he need a second WIS SAVE to get the second attack roll in?

Question 2: If the Attacker made his Initial WIS SAVE and made his melee attacks, would he need a second WIS SAVE to cast Spiritual Weapon afterwards, or does the first successful save essentially end the spells protection against all future attacks by that attacker?

Quote from Aristodeimos >>

Situation: An attacker wishes to move up to a player with Sanctuary and use an Attack Action to hit him with an axe. The attacker gets two attacks per Attack Action. The attacker then plans to use a Bonus Action to cast Spiritual Weapon to again attack the defender with Sanctuary.

Question 1: If the Attacker makes his initial WIS SAVE against Sanctuary, does he get to make both attack rolls, or does he need a second WIS SAVE to get the second attack roll in?

Question 2: If the Attacker made his Initial WIS SAVE and made his melee attacks, would he need a second WIS SAVE to cast Spiritual Weapon afterwards, or does the first successful save essentially end the spells protection against all future attacks by that attacker?

1. Each attack requires a separate Wisdom saving throw. This is because the spell says "targets the warded creature with an attack", which is something you're doing twice in this scenario. It would say something like "uses the Attack action against the warded creature" if it were meant to be a single saving throw.

2. You would not need to make a saving throw just to cast Spiritual Weapon, but you would need to make a saving throw each time you actually want to attack with it. I don't think  casting Spiritual Weapon counts as "targeting the warded creature with a harmful spell" because that spell doesn't actually target anything, it just conjures up something. You can try to attack with it as part of the same bonus action, and then you would need to make a saving throw.

So the components are verbal, somatic, and material. Do I have to do all of them or can I just do verbal and not have the material

You get a Sanctuary and you get a sanctuary, everyone gets a sanctuary 

But why a small silver mirror?

Funny enough. you can still grapple with this spell or shove, sinc ethose arent attacks or cause damage on thier own.