I have a player who is a Genasi Swordmage with the Stormsoul manifestation. He has the Elemental Assault feat, which gives him a +3 thunder damage bonus on melee basic attacks. Does this give his basic melee attack the thunder keyword? Specifically, I'm wondering how and if it interracts with his Promise of Storm power from his racial manifestation. This power gives him an extra damage boost of 2d8 (at 11th level, which he is at) on attacks with the Lightning or Thunder keyword.
Any help would be greatly appreciated! Thanks!