Since MMs are sort of snipers and snipers are often specialized in penetrating armor, why not make them ignore armor? My idea is for MMs to ignore any defense/buff monsters have including the enemy's weapon def, the def up damage debuff(like in ht/zak arms) and weapon cancel Since snipe used to work on weapon cancel anyway it's logical to turn it back, and as a buff for the class make it work on strafe and other skills as well. In bosses with no cancel/def up it will be a rather minor buff that only gives like 1-2k more damage per hit (depending on the monster def), but in things like zak or HT hitting through cancel and ignoring def buffs could be quite powerful.
Is an MM buff even necessary? According to the DPS chart here https://royals.ms/forum/threads/4th-job-skill-changes.135025/ They out dps most melee classes, and are only slightly weaker than BM. Add the fact that they have one of the most sought after buffs in the game, SE, i don't see why they need a buff in the first place.
Maybe dont buff them with Attack, buff them with HP instead to make them really the budget Ranged Class
