There are now two sources about this new class.
What clue do we have ?
1) it's name : it's war related.
2) it's role : it's supposed to be a leader
3) the fact that the Bard seems to be out. There is stuff to steal.
4) older classes, like the marshall, the aristocrat etc...
I think the warlord will be your typical charismatic leader, with good social and leadership skill. Something akin to Starwars noble. You wanna play the lost heir of the throne ? You need an archvillain that is not a wizard ? Here is the warlord, with decent combat ability, and able to inspire his ally with courage and determination.
The remaining questions is: will he have spells ? I fondly remember the first "warlord" I played, in a Steve Jackson game (no, not gurps, the other steve jackson) it was a spellcaster with martial skill...