@AzulCrescent there is nuance between a hammer and the glorified bagpipe named Hunting Horn.
The are both blunt weapons but damage charactaristics are different.
Generally each hit with these two thingies does generally deal exhaust-damage in extra to their normal damage. Exhaust-damage that hits the head is counted as stun damage instead.
A hammer is better with stun damage thats why you see hammer users mostly aim for the head. Do enough stun damage and the monster will see starts for a short time.
Horn is better with exhaust-damage so you should try to aim anywhere else than the head if in a group with a hammer player especially. Deal enough exhaust-damage and the will get exhausted and drool for a little bit and stand still while doing so. So there is incentive to play super aggressive with the Horn and make sure your Hits (that all go different directions) land
Its kinda like a dance almost when you have it down :D
Also always make sure to have the "self-improvment" song up when playing horn. Makes you faster and stronger. Happy Hunting!