Personally, I'd go with the PHB II option. He'll be penalized until he levels, anyway. Retraining is a beautiful piece of writing, and it adds so much realism to a game that it isn't funny. To honsetly think that a fighter isn't going to change his style over the course of years of adventuring is a bit silly.
Seriously. In another thread about something totally different, a point was brought up that some DMs out there hate when their players plan out their character to level 20 - as if the adventure to get to level 20 would have no impact upon the character. While I do enjoy looking at the possibilities, I don't plan anything concretely because I expect the adventure to change who the character truly is. To expect the same out of a fghter and their weapon is just a bit to stringent for me personally. That's why I love the PHB II retraining rules. A fighter can change the feats, but only at level-up.
I would say that changing WF (pick a weapon) would automatically change the rest of the following choices because WF is a prerequisite for WS, GWF, and GWS. Changing the root feat therefore should change the rest of that chain.
But then again, ultimately I'm out to have a good time with my players. If they want to spend their 1 change per level on switching out their weapons, great! Their having fun, and game balance is certainly not being compromised!
I do like the polymorph any object rule, though. That was a cool one. Personally, though, Psychic Reformation is my favorite solution. That would change the feat just like is suggested by the PHB II ruling.
Then again, if the player is frustrated, use the PHB II to send him on a rebuilding quest and turn that fighter into a wizard with a whole new selection of feats! That would also solve the problem ... because then neither weapon would look attractive.
