VERY BIG HITBOX/BOUNDING BOX CAUSED BY CUSTOM WEAPON

GOOD DAY GUYS ANYONE CAN HELP ME SOLVE THIS PROBLEM, I HAVE THIS CUSTOM AXE OR HAMMER A BIG ONE, HOW CAN I MAKE THE HITBOX/BOUNDING SMALL LIKE THE OTHER WEAPONS.. THANK YOU TO THOSE WHO WILL BE TAKING THE TIME TO HELP

USE BLENDER OR 3DSMAX TO RESIZE THE WEAPON TO HOW YOU LIKE IT ... EXPORT IT FROM ATOOLS -> OBJ SO YOU CAN OPEN IT IN BLENDER/3DS MAX

Good Day sir my problem is not the size of the model itself, im ok with the model but I am not with the hitbox, is there a way I can use a smaller hitbox/bounding box without affecting the size of my axe model? Thank you so much for helping