Lord Sessadore
Explorer
I agree with Ata. Reason being that double weapons as written carry the off-hand tag, which means that tempests get bonus damage with them. While two-bladed warrior can give the same damage dice as a double weapon, the tempest gives up his bonus damage to do so, since neither weapon will be off-hand.Assuming MP is approved what about the ranger multiclass feat two bladed warrior. It gives you skill training in a ranger skill, the ability to wield a non-off-hand weapon in your off-hand, and then the ability to take paragon fighter classes. Is a double weapon still too strong?
Whether it's enough of a tradeoff is another question entirely, but I don't think that two-bladed warrior balances double weapons in any way.