An interesting think to think about when coming up with a name...
Most D&D classes fall into two big categories: descriptive and occupational. Descriptive names describe what the class generally does (rogue, fighter, sorcerer, wizard) while occupational classes describe a job or title the character has (bard, paladin, druid, monk). A few classes can reasonably fit both (cleric and barbarian appear both descriptive and somewhat occupational). A way to think of this: Imagine a character explaining his "class" to someone in game; if the character wouldn't use his class name ("I'm a fighter") its descriptive; if he would ("I'm a paladin") its occupational.
A descriptive class has the advantage of being more generic and hence covering a wider swath of archetypes: a fighter can be a solider, knight, mercenary, tribal warrior, or hunter easily (assuming the right background and such). A druid, on the other hand, tends to be one thing: a nature priest loosing connected to the druidic order. The advantage to that is that he has a tighter focus and thus more interesting things: by not trying to cram every shaman, witch, and animist archetype into the druid/nature priest class, he can develop interesting abilities like wild shape. Of course, the downside is that narrower focus = less ways to take the class in new places. Its not a surprise to me that the more narrow-focused classes (ranger, bard, druid, barbarian) tend to have less subclasses than the more broader ones (rogue, fighter, wizard, cleric).
Now, what does have to do with our "warlord"? Well, lets look at some of these names suggested. Some of them are more descriptive-types (tactician, for example, is not what someone calls themselves) while others seem much more occupational, be it military (commander, marshal, banneret) or governmental (consul, noble). The former has the advantage of being broader (a tactician can be a military officer, a young peasant girl with visions, or a wise chieftain of the hordes) but his abilities must be broader and less defined. The occupational ones can develop more interesting and focused sets of abilities, but will inevitably leave out some archetypes the descriptive one does (its hard to describe the chieftain of the hordes as a banneret or the young peasant girl as a consul). That also said, it might be easier to integrate a more focused class into an ongoing game since the class isn't trying to cover a wide swath of archetypes all at once.
Now, what about "Warlord"? Descriptive. Few people would describe themselves AS a warlord (probably the same amount that would introduce themselves as "rogues") but it does punch up a warrior/leader vibe without denoting a specific military rank or government position. As for negative connotation; its probably on par with "rogue" or "barbarian" or "warlorck" as far as those go.
So that's something to think about.
