only my opinion but: if you think dagger is not fine in 1.5 you should really think about a classchange. Cauz it wont get better on 2.0 unitl a decent level on 3rd class.
The Damage is fine. The only (small) Problem is that you need full buff, fire dance and VS active to deal propper damage (a lot of other classes do much better w/o BD in my eyes).
... if you have also access to a cat - you often one hit soft targets.
If your enemy is a bit lower on level you can deal near to 5k dmg on gladi with lucky crit backstab (not happend only one time).
And there is have "Half-Kill" atm.
Also we should not forget that if you manage to land a backstab - the damage goes directly to the hp!