Another potential board wiper spell you could run is Harsh Mercy. It would do nothing against other Tribal decks, but you would be completely unharmed by it.
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I agree that Ajani's Mantra should be removed, along with Lifelink. Unless you have an alternate win condition, lifegain doesn't win games, it just helps you not lose them. Demystify, Revoke Existence, and Aven Cloudchaser are great sideboard cards against heavy artifact and enchantment decks, but dead cards against creature-based decks. In my opinion, Pennon Blade costs far too much for what it does. You're spending 7 mana for what could be +1/+1. Strata Scythe, on the other hand, is much stronger. Lands are a lot more likely to stick around, making it far more likely that you're going to get more for the 6 mana you spend here than what you get from Pennon Blade. Bladed Pinions, Whispersilk Cloak, and Veteran's Armaments are all very strong choices. You have a lot of creatures that increase your ability to block large numbers of attackers. That kind of a defensive strategy will crumble if you don't have a way to keep those creatures alive. The 3 Holy Days and the Safe Passage won't cut it. I'd cut away some of those in favor of the more aggressive cards. Hazda Shield Mate is nice, but in order for him to be really effective, you need to be able to pay at least WWW every turn. Consider Story Circle instead. For a deck with so many high-cost soldiers, consider running Preeminent Captain. Where I can really see this deck falling apart is in its lack of removal. If your opponent casts any creature you can't deal with, you have no way of getting it off the table. You have a lot of options here. Swords to Plowshares, Path to Exile, Oblivion Ring, Journey to Nowhere, Wing Shards, . You could even run Day of Judgement (or Wrath of God, if you can afford it) or Cataclysm; you're deck can probably recover from any of those.
I considered doing so, but I would have to take something out for them. The Auriok Steelshapers are one of the lynchpins of the deck. The Kor Duelists are far too good, offensively, to remove to add a slight boost to the offense or defense of my entire board. The Catapult Squads are the only real defense against flying, other than the removal spells. The Daru Warchief each provide the benefit of a Swordsmith and 2 Armorsmiths. The Deftblade Elites are both excellent blockers as well as removal (when combined with Catapult Squad or any equipment). The only remaining creature I could replace is Leonin Shikari, whose ability is far too useful. A friend of mine runs a soldier deck with Veteran's Armaments. While I don't run that in mine, it's a very good card for such a deck. You should consider it. Also, if you run Catapult Squad, remember that Veteran's Armaments is a Soldier and can be used to activate Catapult Squad's ability.