So sounds like you are complaining about mortar kit not grenade kit. Mortar has the projectile arc necessary to clear siege effectively on walls. It does considerable damage when you run full glass and combo with quickness from gyros. The counter play is to just attack him when he approaches lol. Reflects are also effective. If you're a necro focus 5 + axe 2 would do the trick.
You are basically asking for a CD on an auto attack.