I think the way you're playing the Warlord is giving you the impression that he is weaker. Against any mage that can be reasonably aggressive in-school, especially the Forcemaster and Warlock, his conjurations are in fact a liability rather than in asset. His real strength comes in his repertoire of creatures, spells, and abilities that suit just about every situation. His best card is easily Thorg, the strongest defensive creature in the game. After that, it's all about what you're playing against...pretty much all of his creatures have a given situation that calls for them, and proper Warlord play relies upon your ability to recognize what situation you are in and respond or anticipate with the proper creature. Obviously, this takes a good understanding of the rules and game to execute, but the Warlord and Forcemaster are pushed as more advanced-level mages after all.
After being on the receiving end of proper Warlord play, I can describe the Warlord in two words; brutally efficient. He's not initially as flashy as some of the other mages, which sport massive angels and demons who have a lot of immediate power, but his ability to survive an initial assault is mostly unmatched (the Priestess is probably the best defender) and his forces keep getting stronger as the game progresses at no cost to the Warlord. While it is indeed true that at first the Warlord plays defensively early on in the match, as the casualties mount, he easily transitions into a more aggressive mage.
Perhaps one of the most overlooked aspect of the Warlord is his sheer access to cards with the sweeping trait. Experienced players know how effective sweeping is...it's virtually a free attack action against the opposing mage in most circumstances. With Sir Corazin, Dwarf Kriegsbiel, and his Hammer, he forces his opponent to make a tough call; should you summon more creatures with which to guard in order to circumvent damage to your mage? But if you do...you're virtually guaranteeing veteran status for his units when he eventually kills them. If you don't, well...you better hope you can trade blows as well as the Warlord and his squad can. In either case, the Warlord excels at forcing mages out of their element, making them play on his terms, especially in combination with Thorg's taunt.
As one of the channeling 9, high hp, "aggressive" mages, he falls on a more mid/late-game spectrum when compared to the Warlock and Beastmaster, in which his growing group of veterans shine, which is probably why players seem to be over-emphasizing the role of his conjurations...but his conjurations are far more situational than his actual on-card abilities. He doesn't have the sheer power of a pet Steelclaw or Adramelech or Dark Pact Slayer bloodreaper at first...but once the veterans on Thorg, Corazin and others start kicking in, you'll see how aggressive he can be. Against extremely defensive mages like the Priestess, who excel at keeping creatures alive, the Barracks becomes much more viable.
The Warlord is a powerful mage, definitely on par with all the others. When he is played correctly (i.e., not using conjurations against the Forcemaster/Warlock), I never felt like I could just roll over him, even with competitive Warlock openings. The amount of armor you have to get around is pretty ridiculous and is probably his best overall asset. Play him to his strengths and you'll be rewarded.
