Well MT DRK does some more damage than MT PLD while WAR OT does a crazy more damage when then the others, plus they bring slashing debuff utility.

What OP said is too much but DRK could use some kind of buff/utility, especially when OTing. How about a Slashing Debuff on PS when out of Grit or when not DA'ed, this is just a simple example but could be something more complicated too.