Damage would be too low, I'd imagine. Sure, they need TP to do dances, but when you can hit for 0, what TP is there to gain?
I suppose it depends on skill, stats and gear choices. It could be a viable offhand weapon(if /NIN turns out to be an acceptable sub), but there are a lot of variables that we obviously don't know yet.
Unless M Kris is always useless, Ive never actually seen one in action.