What additional modifiers would you like to see available in homebrew?

Does anyone have any idea on how to create a feat, that can either give multiple choices or just one and ya can just retake the feat, to add a choice to weapon masteries?

Me and my players only play with 2014 classes but I would like to give them weapon masteries, although in feat MODIFIERS ya can only add a specific weapon mastery, like only dagger or longsword, and I would like to either find something made by someone that lets me choose either multiple or lets me repeatedly pick it to add the right amount of weapon masteries depending on the class.