Headwings are a small, secondary pair of wings which are found, surprisingly enough, upon the head of an adult 'cubi. They are believed to be a physical manifestation of the creature's magical abilities.

Speculation about weak spot[]

For a good while, there had been forum speculation about whether cutting off the headwings would kill a Cubi. This speculation was based mostly on a part of the Demonology 101 entry for Cubi:

It is unsure if they are simply decoration or actually do anything(no Cubi would dare let them get cut off alive), though they manifest around the same time a Cubi comes into power.

However, strip #009 of the second part of Abel's Story has Fa'Lina implying that ripping off "all four of your wings" would not kill a Cubi.

When this was pointed out in the strip's discussion thread, Amber chimed in to clarify that the headwings are not a weak spot and that their removal doesn't automatically kill or cripple a Cubi. Of course, blood loss and other side effects still would have to be taken care of.