Will those edges work for facebite skill of the monkey?

Pretty sure no.

Why immstaff so hate monkeys?

It bites on the face.... with it's jaws. I almost see how monkey is gnawing a throat!

Btw, when I was about 10 years old, in zoo I was attacked by a little monkey (i think it was macaco) and it actually bitten me on the hand, as well as took a bit of my hair. The wound was small, but it sure did BLEED a lot. Thank god it didn't bite me on the face

I had a few more ideas for horned forms.

Bruising butt - allows forms that butt opponents to bruise and effect them with an occasional soften like effect.

Armor piercing horns - Allows horned forms that charge to bypass armors similar to the armor piercing needles of an invoker. Not with ever hit but the occasional one.

Clawed swipe - Clawed forms that can swipe away weapons from an enemy can occasionally rip the hand with the claws and prevents the victim from re-wielding for a few ticks.

Focus of the predator - These beasts are harder to distract by others rescuing their victim. Less chance of a rescue on someone being successful.