Right, I've done that with Ichigo already, when she gained the ability to summon multiple copies of her battle fans as her reward/upgrade one month. And in the future, I'd like for her to earn the ability to set her fans on fire/convert them into flames...

And Velvet... part of my long-term plan with her involves her getting her Gem Weapon, and many of her power upgrades serving as upgrades/new abilities requiring said weapon. So for both of them, having an alternative means of leveling up their powers leads to interesting implications...