Polearm Stances & Damage

I still can't decide if a fighter should use Mystery Powder x25 to learn Mighty Cruz stance, assuming that Claude is already able to use it. Having just acquired an undead polearm, I tested it out in Ancient Area 2F using a veteran fighter (STR 7) with family's protection buff (ATK +13%) and Moppet's somewhat-random buffs. The sad thing is that the fighter still cannot 1-hit kill off the Lv.102-105 mobs in Ancient Area 2F without scoring a critical hit.

Curious about what would happen if the fighter was using Mighty Cruz for AFK, an experiment was done using the above polearm by an expert Claude (STR 10) with only family's protection buff.

Test Subject	Level & Race	Blandir Cruz	Penetrar Cruz*	Mighty Cruz
Elviot	Lv.110 Beast	733	805	769
Escudo Preffer	Lv.111 Undead	1957	2149	2054

Note (*): The normal attack of Penetrar Cruz is single-target, unlike the other 2 stances.

Evidently, the difference in normal attacks isn't really significant. At best, it is a range of 30-100 damage. So, Mighty Cruz isn't that big an improvement for AFK. Then, if a fighter is to get Mighty Cruz, it is for the skills, which are probably used in raids, boss fights, etc. But if you are using polearm in those situations, why use fighter instead of Claude? Hmm.