We recently got this from the new Eluned bags (similar to the Mabinogi Eluned bag school outfits that I mistakened for gachapon items initially...)
http://luoqi.tiancity.com/homepage/article/2013/08/21/41226.html
[Image: http://i1282.photobucket.com/albums/a521/yogurticecream/mabinogicn/mb0821b02_zpsf2e4c86f.jpg]
[Image: http://i1282.photobucket.com/albums/a521/yogurticecream/mabinogicn/mb0821b05_zps0ecf17a1.jpg]
*Also, that's the blue hair I was talking about for humans in the cheerleader picture.
Personally I think the cheerleader outfit takes inspiration from the female Hebona robe.
The special actions are from the weapons (not outfit), and would override other actions from other outfits. Cheerleader one/female-only is a mace-type one-hit weapon with max attack of 150, cannot be wielded with shield. Did not get to test the male-only bat though.