I guess a suggestion I could make would be:
1. Just simple use C instead Z, so it's X and C, and not Z and X. That's the closest layout to the current one which would help remove the "Z and Y is switched on some keyboards" problem.
2. or you could really give "Roles" to each hand, so left hand moves with WASD and Right hand controls attacks with Arrows, Right Control, and Right Shift. That way you have one hand that focuses on movement and the other that focuses on Attacking.
3. or just add the ability to let people choose their keboard layout.
That's just some suggestions ^^
I hope that's some food for thought.