#birb fact: wing trimming isn't supposed to be traumatic or permanent but I'm sure the Fed could find ways to do it hella wrong

[paused-waterfall]

My interpretation of Phil using a backpack for balance:

The bag isn't literally a counterweight; the backpacks are inexplicable black holes of storage, and the feathers that would be trimmed in a normal wing clipping are incredibly light. Those weights probably don't even out.

But if his wings weren't clipped carefully, and either bone or muscle was significantly damaged in the process (struggle?), maybe Philza's issue (other than lack of flight feathers) has been an inability to hold his wings closed. The backpack might not be a counterweight, but rather a sling to keep his wings from flopping around. Phil might be able to deal with changes in how much weight he's carrying, but not with the constant changes to his center of gravity that broken wings could cause in a fight.