Is it permissible to wipe the hands on a clean abaya during Wudu'?

It is not permissible to wipe over the abaya instead of wiping the head during ablution, because the abaya is not difficult to remove. Wiping over the khimar, however, is conditioned upon it being difficult to remove and being wrapped under the throat. As for drying the hands with the abaya during ablution, there is no harm in that.