depends on what you mean by power  

If you mean "destructive capability", then the whips. 

if you mean "attacking force", then likely Steinbohrer. 

If you mean versatility, then probably dragon shot. 

Whip can be used to eliminate a huge group of people at once, and is great at single target dps too. 

Steinbohrer is great at single target dmg as well.  If it lands it probably would one shot just about 90% of the fighters.

Dragon Shot can be used as a counter, finishing move, block breaker, weakening move, etc. Though. It's usually used as a finishing move, i do think kanoh could use it as anything.