Ok, this one's simple. Is it possible to make some low lvl wings specifically for being slotted? I think it'd be really cool to utilize the swordy combo while wearing wings. Maybe make a pair that gives the same def as slotted full plate, or maybe 8 def and +1 str?
Zodiac and hero wings are slotted, others are not. This was done on purpose, this is one of the disadvantage to the elemental wings for example. It keeps balance.
Heroic wings are earned in the ToH monthly event, see the chronicles section for more details. Zodiac are made with a quest, the NPCs to start it are in Yuno, can't miss them