Things like weapon trails, impact effects, and air distortions can successfully convey a physicality to the move compared to magic, while still allowing the special actions to be easily discernible from standard attacks or movement.
Absolutely, but they should be kept minor and be used to separate melee skills, not be generically added for "cool effect". Using too much of an effect is the easy way out for uninspired or time-constrained developers. Proper sound effects paired with well-tuned animation, target reaction and on-hit effects like blood goes a long way.
