Any proper review is cheating since I was fond of the source material to begin with, but you sure pulled it off, boss.
However, If planning for new class in future, why not enable option to upgrade equip of 1 mainclass & 1 subclass, into equip 2 main class? Requirement: 2nd main class should be at least level 60.
Instead of gaining 2nd equipped class subclass benefit, it gain the mainclass benefit instead, including the weapon mainclass benefit too.
i) High defense, sword main, & able to buff party member? Hunter Main + Techner Main (Paladin)
ii) Want to punch & kick hard? Fighter main + Bouncer Main (Martial artist)
iii) True all-range magician? Force main + Techner main
iv) Magic gunner? Magic swordman? Monk?
v) Weapon master? Ability to use more weapon of their full potential? Not that one may use it all, just keeping the possibility. Also previously one said "Multi Weapon", to multi more than 2 weapon together, this can work well.
Why:
To not render existing class inferior to new class, like Slayer, i like the class, but really, it's very powerful. Too powerful perhaps, that you need to constantly balancing other classes. I heard you're going for new successor class? Why not try this instead?
Additional reason:
Again I say, what happen only is, instead of gaining 2nd class subclass benefit, one can get its mainclass benefit instead.
May or may not consider my suggestion, just please whatever you do, don't abandon existing classes, or create another overly powerful class that render other class inferior, again.