I don't like the Ifrit battle: rant warning

[Rentahamster]

Why does Marauder need Defender and enmity-generating moves when it's not the primary tanking class?

It still has tanking characteristics like high HP and defense, and can be built to be a suitable tank.

Why do Pugilist and Lancer both get healing moves like Second Wind and Speed/Life Surge?

Life and Speed Surge are support abilities and debuff abilities, befitting a DD like lancer is supposed to be. Why shouldn't pugilist get a move that's like "Chakra"?

Why does Archer get Decoy?

Because using decoy is part of an archer's gameplay when soloing so you can buff multishot and avoid the first hit as you kite the mob.

Why does Pugilist get Accomplice?

Because it's also another class that can be used to tank (at least that was the intention. evade tank). It also has taunt, too. It's designed that way.

All of these seem like tanking moves to me, yet they're learned by jobs that aren't really designed for tanking in the first place...

Marauder and Pugilist are designed for some kinds of tanking. The only job that was ever a tank that was not designed to be a tank was Thaumaturge before the Emulate nerf.

The other skills that you mentioned have uses that are not just for tanking and have other useful applications as well.