Hm, give avian wing a combo similar to garm hat/arctic wing and maya helm/gaia wing? Maybe avian wing can go with one of the custom hats or hatter hat to give agi/flee to rival that of the existing pantie/undershirt combo.
Increase aspd slightly perhaps? Or give it +another stat that isn't agi to make it less...unless...perhaps reduces damage by a small percent from maybe earth or wind or even nuetral?
Adding a slot to the avian wings would be really nice. If you are feeling really evil make it slotter obtainable only... I don't think the item list should be changed though. Blue and Red feathers aren't hard to get. You don't have to go past level 2 in thana tower if you don't want to. If you can't survive in there then go level and try again later. If you don't think the item is worth all the effort it takes to make it then why are you making it in the first place?