I feel like it has multiple abilities, and its form changes accordingly.
Reason: it is shown with a sheath on and another off, so I think the sheath off is no guard and sheath on is some other (possibly defensive) ability. Also, this would be a cool way for pokemon to reflect what ability they have. --- I don't suffer from insanity; I enjoy every minute of it! My SSB4 roster: http://tinyurl.com/ctaqf3x