I agree, Arlemus, that both the Forcemaster and the Warlord suffer from their weak schools more than any other mage. They are the only ones that are actually required to dip into their weak schools in order to make a viable build. However, the Forcemaster's play style is much better supported by the current card pool. She was actually considered overpowered for a brief time, before errata to Battle Fury. Her power has been in steady decline since her release, however, and the weakness for creatures is definitely holding her back from where she would otherwise be, but she remains viable because the cards still support her being super aggressive and killing her opponent before they have time to properly respond.
In comparison, the Warlord seems to want to swarm the field. There's already debate about swarms even being viable, and so many people would consider that to start him off with a handicap. Then you add in that his spawnpoint has not been considered very good, and his swarming play style goes down the drain. Finally, his Veterans ability is somewhat subpar because he has no control over it or any way to predict it's usefulness. It depends entirely on what strategy and creatures his opponent decides to use as to whether it is any good. All of the Forcemaster's abilities are good. The weak school tax definitely exacerbates things, but it's not the only thing.
That's taking a look at how things stand pre Forged in Fire. The errata to Garrison Post and all of the new cards being released will definitely change the playing field. But you are correct that the weak school tax affects both the Warlord and Forcemaster, it's just that there's a lot more going against the Warlord. I do not consider him unplayable like some have stated. I've seen him do very well with an Elite Squad of troops. However, he is definitely the most handicapped of the mages.
Well I think you targeted the problem, but it's not with the Warlord, it's with how people understand the Warlord and then play him based on those understandings.
I agree that many people see the Warlord as a "swarm" mage, and I thought so too for a while after he came out, but it's a false view of him. Another false view of him, one I also believed for some time, is that he is a leader of an "elite squad." The truth about the Warlord, one I hope other people start to recognize, is that he is a leader of an
efficient army.
The problem with swarming as the Warlord is that he simply has no real ability to swarm, and it doesn't have anything to do with his spawnpoint. To be a "swarm" mage, you need the be able to bring in as many creatures as possible every turn. The two mages that I would say have the ability to swarm are the male BM and the Necro. Both the BM and the Necro can, if played to support it, bring out 3 creatures every turn. The BM accomplishes this through his full action, quicksummoing, and lair; the necro accomplishes this through his full action, Mortos, and graveyard. In comparison, the Warlord has only his full action and spawnpoint. If you're going to swarm, however viable it may or may not be, you simply shouldn't do it with the warlord because he has no ability to bring out any more creatures than the standard 2 a turn. The reason people believe he needs to swarm is largely because of implications brought about by Standard Bearer and Akiro's Battle Cry. While both these cards benefit from having a large amount of creatures, it isn't enough reason to believe that the Warlord can or should swarm.
Now lets look at the "elite squad" build. This build generally centers around having a few "elite" units that you support. I believe this build is more viable because it's at least not weak to zone attacks, chain lightning, etc, and at least battle orders help you to support your "elite squad" in some small way. The problem with this build is similar in concept to the problem with his swarm build; the Warlord simply doesn't have any innate ability to protect/support his troops, other than his situational battle orders. Basically, the priestess can and does do the same thing (larger creature support) and is better at it. She doesn't have to pay triple for dispel (for the inevitable curses, etc, that will be placed on your bigger creatures), but more importantly she has an innate ability to counter status conditions like sleep, stuck, etc, which are the biggest downfall to big, or expensive creatures (IMHO).
So, after experiencing these two problematic archetypes for myself as Warlord, I finally came to the conclusion that the Warlord is instead the commander of an efficient army. This means a few key things to me:
First, the centerpiece of your soldier army is the orc butcher. Butchers are hands down one of the most (if not the most) efficiently costed units in the game. Butchers are the lowest cost way to access a creature with a 4 dice attack (IIRC), and they are extremely efficient at 10hp and 1amor for 8 mana. Butchers are not really worth enchanting because while they are efficient, they aren't the sturdiest to gain enchantment value from, but that's OK because as a level 2 creature that means they aren't worth cursing or controlling either, and they're also prime targets for temporary buffs (aka commands/incantations).
Second, you're going to be using barracks, but you aren't going to "spam." You're going to get board presence with butchers, because they are the most efficient way to do so, and answer the other mage in an appropriate way (acid ball armor stacking, making a bigger soldier, etc). Most of my games I average 3 butchers. I wouldn't consider that a spam; use grunts to fill in for butchers on turns you need more mana, and minor heal the butchers when they get to half hp or lower.
Lastly, meditation amulet. Meditation amulet is the generator that fuels the Warlord's efficient army. It makes up for the relatively costly opening, and gives your full action the best way to generically influence the game, i.e. mana.
It feels like I'm explaining a particular build now, but I think it's for the best. It's obviously more complicated than that but I'll stop here. I'll agree that the Warlord had problems (like dealing with armor pre-DvN) but after DvN and especially now after the outpost errata, I think he's no worse than any other mage, and better than some. I know it's heresy to think think the Warlord is a good, even strong, mage but I really don't think there's anything going against him that isn't player based, rather than game based.
TL;DR:
1) The warlord has no swarm capacity.
2) The warlord is no better or worse at supporting an "elite squad" than another mage (maybe slightly).
3) The warlord DOES have access to extremely efficient creatures and commands that give him an edge.