Quote from Wgaming113 >>

Quote from gaber11979 >>

Quote from Eldritch_Queen >>

Ah, this was my very first magic item. I've had so much fun using this thing.

 My first two :-) 

 mine too, in my first game i played a dragonborn paladin and cast searing smite on it to slice a centaur in half and dealt double fire damage

 Sounds fun

Brisingr

Roughly doubling your DPS seems way too strong for a rare item.

This is easily the best combat magic item, probably OP.

That’s epic

Quote from Riesenfriese >>

Roughly doubling your DPS seems way too strong for a rare item.

This is easily the best combat magic item, probably OP.

 Yes, I think it's definitely overpowered for it's rarity rating. It should be at least Very Rare: 

First, a +3\+3 weapon is "Very Rare", yet this "Rare" weapon does +0\+7. 

Gauntlets of Flaming Fury (also Rare) add +1d6 to any nonmagical weapons you're holding, giving dual wielders two +1d6 weapons, Gauntlets of Flaming Fury uses the same Bonus Action to activate, and also lasts until you sheath or let go (of either weapon)... Except that Gauntlets of Flaming Fury can only be used once per day! Flame Tongue weapons cite no such restriction, activating over & over for any fight at no cost except a Bonus Action. 

Unless doubling as an easier-to-light torch is counted as a detriment, Flame Tongue weapons are much more powerful than Gauntlets of Flaming Fury, comparable even to a +3 weapon. 

Seems obvious that these should be Very Rare?

The Monk in the campaign I'm running tricked me into giving them this. The party is level four as of now, but the monk has a strength score of 20 so they can get insane combos with this sword and unarmed strikes and do something like 40 damage a turn for a ki point. What do you suggest to counter or remove this sword? I'm pondering putting a curse of some sort on it.

If the item is sentient then it could choose to tell its wielder the command word.  or it is written in a unkown language on it

Gonna give this item to my Dracoian (Like dragonborn, but are actual dragonkin) Sailor NPC. It will be so fun

Ouch! That must have been fun.

Is there an official equivalent of a Flame Tongue weapon for bludgeoning weapons, like warhammers or mauls? 

Can you put a + to hit on Flametongues? like a Flametongue+1 is that possible?

This is legit almost everyone's first weapon.

Personally, mine was just a boring +1 longsword, so...

( Speaks in Leonin ) 

This is really good! I have used it in the”Rise of Tiamat” campaign.

Quote from ChrisAu >>

When I DM, I also consider how hard it would be to find a customer who is willing to pay that much and has the money available.

 Just make it a weapon you can find in a dungeon or loot from a boss

unfair that daggers dont get these

What is the att bonus if this is on a long sword?

my great sword gives +5 att bonus.  

Why are these fancy magic weapons always limited to just swords? Would it be so wrong to have a flame tongue battleaxe or a holy avenger warhammer?

I know homebrew is an easy fix, but it would be nice if the official material wasn't so preoccupied with such a narrow subset of weapons.

can it be sentient?