The PoHs are irrelevant in games which take place after KH1, that is, until KH3 comes along. And look how 'important' Maleficent was in KH2. She was there being a minor hindrance for a few worlds, helped SDG out in the middle, then completely disappeared for the rest of the game until the World That Never Was, with no explanation on how she even got there or what she was doing during her absence. :\
I'm talking about Disney characters who are not Mickey, Donald and Goofy. Despite Disney being a large part of KH2, the stories related to Disney has been so mishandled that the notion of Disney characters being important to the main plot has been raped hard except for a few notable exceptions. Days was excusable because of the setting and the main characters that game is focusing on. BBS is bringing it back again!
Actually, since the entire series is owned by Disney aside from FF characters, Sora and co. are Disney characters as well.
So, are we to assume that Star Seeker is Yen Sid's actual Keyblade, or a more powerful version of it?