User blog comment:FairyRaven/Fairy Tail Chapter 333: Man and Man, Dragon and Dragon, Man and Dragon, Review and Commentary/@comment-5105419-20130603035234/@comment-7418318-20130605091206

The figure in the picture was only warding against an attack by the Dragon, so it's possible it isn't a Dragon Slayer.

Though I think most likely it is showing a Dragon Slayer... or maybe Zeref, but I somehow doubt it.

Maybe it's even a picture of Acnalogia, still in Human form, killing another Dragon... even though that would contradict Zirconis' comment about Acnalogia being the only Dragon with black wings.... but then Zirconis isn't exactly trustworthy in my opinion or the drawer might not have known that.