PLD vrs WAR

[BlaiseLallaise]

Well it's obvious you don't understand what's going on here, and I doubt I can explain it any better than anyone else has already explained it elsewhere, but here goes.

Gladiator = class.
Paladin = job.
class does not = job.
When using a sword, you are always a Gladiator, even when you are a Paladin.
A job has a symbiotic relationship to a class. Meaning, a job (PLD) cannot exist without a class (GLA).
What a job (PLD) does is force a class (GLA) into a specialized play style (Tank) at the cost of being able to use abilities from other classes (PGL,LNC,CON,etc), or other play styles (Damage).

So, when you ask "Why have 2?" the answer is "There is no 2. There is only one."
Trippy, huh?