That's good for games involving giant armies...but how does that work in a game that revolves around a small party of 3-6 individuals? Plus, most players don't like being told what to do just because one guy decided to play a "Warlord".
A less "I outrank you!" name would be better and would help to sidestep these sorts of issues.
The name "warlord" doesn't imply that he gets to boss around other characters any more than the name "cleric" implies that the character is Muslim.
Furthermore, the role is (probably) that of a Leader, and "Warlord" is a suitable leader-y name, cementing the class's relationship to its role. Having a name that didn't imply that the class filled the role of a Leader would weaken that relationship. People follow a warlord. Likely, teammates will follow the Warlord-class character, too (because the mechanics of the Leader role, I assume, will encourage it).
Also: "This barbarian warlord from the Northlands has joined our sacred quest for the McGuffin!"
Also: "We have recruited one of the warlords from the orc tribes to help us tame the goblin infestation."
Also: "The wizard knows a warlord who has helped him before."
I mean, to me, "warlord" implies that you rule directly through military might a rather small force. That force probably isn't the other PC's, but it could easily be some of the rabble outside of the cities (or even some of the rabble inside the cities -- generals, guard-captains, etc. could all be good warlords).
And given that the names of classes are obviously not meant to be taken entirely literally (cf.: your cleric isn't a Muslim), I'd say this shouldn't be much of an issue.
Sounds good, but she's clearly a divine leader, making her a cleric, right?
#1: If a 14 year old girl could kick my ass, I'd probably whip up an elaborate mythology quick to explain why.
#2: The line between "divine" and "heroic" is blurry at the best of times.
