Maybe Ven hold the Kingdom Hearts?
I'm thinking it has SOMEthing to do with Ven. Because the fight kinda just halted when MX got ahold of Ven. MS seemed to be satisfied, Terra and Aqua looked genuinely and intensely worried about him having Ven, and MX seemed bound and determined to hold on to him. Christ, he broke his armor with his bare hands. (Well gloved but same basic idea. <.<)