taking your fingers off the face buttons to control the camera sounds kinda lame.

(use wiimote/nunchuck for tri- can move, use camera, and switch between attacks without compromising hand placement- thank you capcom)

From this I have devised this idea,

You use the analog circle pad for movement (first thumb)

You use the face buttons X,Y,A, and B for camera (second thumb)

Index fingers for the shoulder buttons- attack and dash or dash and attack

the only properties being left out are shielding and dodging

if you're blocking you may not need the camera  and could just use your right or left thumb for the touchscreen. (input would be on both sides of the touchscreen for reasons stated below)

dodging is a bit trickier and would rely on the player setting up their camera angle ahead of time then blocking.

having the input for block and dodge along the corners of the touchscreen would allow players to change the camera angle and dodge with their left thumb (if in motion, why would you need to move?) or block and move- lancers please use your right thumb to block.

the middle of the touchscreen would be for items and ammo; the layout similar to MHtri.

Oh yea, and the types of attacks...maybe the attack button could be pressure sensitive much like street fighter games on the gameboy advance? The amount of time you have pressing down on the attack button would change the type of attack.

An alternative, not my favorite, would be to utilized the Dpad for the type of attacks, ... after the inital attack you could then choose your combo. This would limit your initial attack to be the same.

Update: forgot that if you try to run while wielding a weapon you'd block anyway. That and I still haven't addressed the input for wielding and sheathing a weapon...Touchscreen or select?

Have you ever played Monster Hunter?
Instead of all this overcomplicated and ridiculous scheme how about taking the inventory to the touch screen and the same way you would use the inventory (L y or a) you use the camera?