Why? Pick one feat, the one about "fly while carrying additional weight", say. That lets them fly *as long as they're carrying additional weight* - if they're not being used as troop carriers, give them ballast of some sort.
You *might* want to consider either giving them a skill better than the standard 13, or the temporary loan of an item that makes Vanganthi magic work better. Or a nearby NPC who has such a gadget, with an area effect. Stay close to him!
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