Whenever the GM makes a ruling in favor of a player, that's more fun for him.
Whenever you state that RAW is ambivalent, and the GM can interpret how he sees fit, you empower him.
When you try to weasel out with weak wisdom to force feed your fantasy, you put your GM in a weak spot.
There's nothing worse than munchkins going forum-shopping until they get the answer they want and pressure their GM. I'm sure most of you have seen that happen. Dishonesty should always be stumped out.
Even if most players agree with SA that your pact weapon is locked out in a single shape, you can still ask you GM to give you a little freebie. He'll judge if there's a downside or not.