That's something I'll be adding for my own project. The only way I can think of doing it is by going into each enemies melee animations and adding a flag that spawns a particle projectile. The projectile only goes so far before destroying itself. If it hits an object it makes a sound and spawns blood or sparks or whatever. I've done this for the warblade, razor wind, and nuke weapons already but I did it by way of script. I'm sure it can be done using the Fireseed model and animation editor for monsters which I think is the best way to do it.