[Snake]

I don't know if it's called 'Forbidden' because it's dangerous to use, or because it's a complete bait of a potential skill. I do have a suggestion on how to make it better or at least more interesting, hopefully.

Dagger's Potential Skill: Inflicts you with Cursed Vengeance LV10 for 5 rounds.

"Cursed Vengeance - Every round, your HP will be drained by 10%, and LV will be increased by the amount drained. Performing a basic attack will use this status to increase its Power by LV, but you will take 50% of your basic attack's damage as protection-ignoring Retaliation damage. (Taking damage from enemies will also increase LV by the damage taken.)"

[caliaca]

I think this is a great way to kill yourself in 2 turns.

[Poruku]

So you're telling me if you take 200 damage while this is active you are now dealing with a 210% increase, so then you use divine eyes to do 900 damage and take 450 damage.

I mean honestly that is hilarious, but I think reducing the HP drain could already get us somewhere. Base dagger is awful, but if you could get 15% bonus damage with a small drawback, maybe 2% hp drain applied as lethal protection ignoring dark damage, then we would be talking. Still gotta use 3m to activate that thing!

[renowner]

Frankly this move has been in -dire- need of an increase in power for ages now and I would LOVE a buff or rework. Though personally, although a reaaaaaally cool idea I feel the rework would, well. . .Turn basic attacking builds into a vaccum. You kill yourself really fast but obtain massively powerful attacks. 1,000 base health means you'd be doing 100 base extra power each round, stacking. Multiplied by your critical multipliers or excel, and you'd basically be critting people for 600, then 900, then 1200 as a dagger crit void assassin. Hitting yourself for half the damage is still a big deal, but I Feel like it'd just sorta make people all play ghost with an excel weapon to do a one shot, and if it doesn't kill, follow it up with an ether invitation. 

Neat concept though. I still feel it'd maybe railroad people a bit. Too crazy to not make everyone gravitate towards using it.

personally i'd rather it just be buffed, but remain similar to how it is now.

My two ideas are:
1 ) Change the momentum cost to zero, and buff the damage increase to 15%. (Makes it slightly more worthwhile to use at that point, 10% Max health is still pretty steep.)

or

2) Keep it as 3m like it currently is, decrease the health drain to 5%, but allow people to stack it up.
Adds 1 level per use, and each level is +10% Damage and 5% Max hp drain each new round.

Spend 14 m over two turns stacking it up, and now you're at 40% Damage increase for 20% Max hp every round. At least then people could have fun roleplaying ki awoken type berserky stuff.

In its current iteration its unusable. I really want to use it, but can't think of a single justification for it. 
3m, 20 fp, on a weapon that's already not ideal. . . So you sacrifice your turn and can't even really use it as a fight ending combo piece. You'd always be better off spending that 3m on another attack than trying to buff yourself up slightly over three rounds.

Even in the best case scenario where you're fleur critting every turn and getting three offensive actions. . .
You get two on the first turn, Three on the second, three on the third.
You've drained 20% Of your max health to do 1.1x damage on 8 hits. Which still ends up less overall than just hitting nine times.

And since its main hand only, you'd have to do shifty pocket stuff to use this with a two handed excel weapon, and even then it still probably isn't worth it.

Only possible exception being Divine Eye on some huge tank. . .But then you're still sacrificing 3m, 20 fp, and lots of health to do. . . thirty extra damage.

Its just never worth it.

(Please make it worth using, its got a cool aura. . .)