Coat litteraly any regular non-magical 2H sword in poison or dip it it fire ... and you just get weapon of exactly same power. O_o
I follow one of your regular advice : I never use dipping

On top of that, you can coat the Everburn Blade with some poison (it does not work with all of them if I remember well, but I can assure you it is with the wyvern poison).
It's not really THAT good. And personally I'll take +1 or +2 weapons that also increase chances to land a hit over a "pre-dipped" flaming sword.
The Sussur one with ì1 and silencing effect is great, for instance. Even if in my last playthrough I decided to go for a dagger and give it to Shadowheart instead.
With reckless attack, the +1 is less impactfull imo.
You can get the same bonus fire damage on other weapons by dipping. Imo other weapons have more interesting bonuses. E.g. a bear barbarian can fight relatively safely at 50% health when raging, so I'd give them the bloodied greataxe (also available early) instead.
1D12 + 1D6
Average damage without dipping : 10 when you're below 50% HP.
Average damage with dipping : 11.5 when you're below 50% HP.
2D6 +1D4
Average damage : 9,5 damage everytime.
Not worth "the risk" imo even if as you said, it's easier to stay below 50% with a barbarian.I personnaly think it's gonna be time to heal when I have less than 50%.