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Before I begin, I want to say I'm a sucker for exotic classes - things that are both flavorful and powerful, but not crazy or one-trick ponies, like the Frenzied Berserker. I come from a background of high power games where the warriors get as many options as spellcasters, even if they're still not the all-consuming power that is magic. Post-Tome of Battle thinking, this.

This class has the flavor, but no power to back it up. It's mostly passive bonuses, with a couple of useless "flavor" abilities. Flavor doesn't mean "I will never use this ever I'm sure". At 16th level, these guys are no better at fighting together than if they had taken synergistic combinations of classes instead. 10 levels is a lot, so you have to have some kind of cool payoff. At the moment, it's on par with Knight Protector and Duelist. Cool on paper, but useless when you put 10 levels of most other cool things onto it. Especially when it's 20 levels in total - 10 for two characters!


That said, I agree with adding a martial manuever progression, and maybe some other things, like:

"Combat Cant" - I think Sense Motive is more apt than an Intelligence check, since you're divining what they mean, not why they're saying.

Change "Hey, Get up!" to 10 * Class level in healing or temporary hit points if the partner drops below 1/2 their max hit points. This way the ability is actually useful, and likely to be used, but doesn't actually heal much ABOVE your maximum hit points. This represents the ability of the partner to lift flagging spirits, to encourage and support the other partner. A second wind, if you like.

Perhaps Twinned Blades as written right now to is not very powerful at all, as you're likely to only hit with your primary and secondary attacks, making it very unlikely you'll get more than +20 damage on the entire manuever, which is equal to a single attack by a rogue, who can do that at will. And since mobility is always good(!), when are the swordsmen going to ever get to full attack the same enemy at the same time? As far as I can tell, anyway. It needs playtesting.

Very nice idea, though. I really do think it has a lot of potential.