I took warding gesture (undead) on a lvl 7 sorcerer cleric 1 (total lvl 8 ) character, and it does not seem to be working. According the feat description, with my boosted +7 CHA modifier, I should be able to fear undead that fail a DC 21 will save. I tested this feat 9 times on groups of skeleton knights in the crypts; so far it has not worked.
Since it doesnt seem likely that all these skeleton knights passed a DC 21 will save consecutively, I think that this ability may not currently be working.