How to fix THF:

A+ dagger

Attack Bonus I through III

Cut Sneak Attack and Trick Attack timers in half for THF main.

Adjust Sneak Attack so that it deals reduced damage when attacking from the side (being in front still causes it to fail)

Adjust Trick Attack so when used together with Sneak Attack being behind another character counts as being behind the monster (you are out of it's sight after all).

Triple Attack II at 75 and Triple Attack III at 95. +5% each. Also raise Triple Attack I to a base 10%.