Also recall that ultra-high-pressure water is very dangerous... it can cut cleanly and quickly through stone, even most metals; vs flesh and bone, it cuts like an uber-blade, a cross between a power-drill and a micro-chainsaw. With Soulfire, even supernatural hardening might not resist. But note that when you swing a water-blade, the blade is liquid: anything that "blocks" it, your swing continues unimpared, and as soon as the blocking object is no longer in front of your swing, the liquid blade re-forms, just as potent as ever, and your swing continues at full speed! You may need to stat it with some sort of "hard to Block" advantage...
However, this is much more than a "weapon". You can cut neatly through doors, walls, etc (even brick walls, metal doors, etc). You can drill very-fine holes. Ultra-erosion in soft dirt. You can cause all kinds of mayhem to your environment, slapping aspects onto a scene...
I also recommend looking up the "Avatar" animated series, and "water-bending"...
Steve, the g33k