Yes, the killer bunny is a fallacy created by pop culture. And, i would not use cartoons to further my argument. But the view that rabbits are not capable of fighting/are not violent is also a fallacy, primarily because people are thinking of bunny rabbits, which are domesticated and kept as pets. Just as a 200lb orangutan can over power with sheer strength, a 200lb man, and a golden retriever will get its but kicked by a similar sized coyote, a wild rabbit is far more dangerous than your sisters lop eared bunny.
Another thing leading to the underestimating of rabbits, jackrabbits or hares, is that they run away from us. This does not mean they are completely timid by nature, and only run away when faced with danger. We are ten times its size! went we perceive a monster to be ten times as dangerous as use what do we do? It is very different then when we come across a couple goblins. the video of the rabbit and the snake shows that they do fight, but shows their dodge skill better. their combat is better shown here
http://www.youtube.com/watch?v=Pk28__1LnZs. And that isnt even them in mortal danger, more like someone is in a bad mood.
But what really needs to be decided a what a racial trait represents. And, what a animal needs to display to qualify. Basically a racial trait is what makes a race different from humans, so lets use that as our point of comparison. What a wild rabbit has that a human does not is firstly incredible agility, hence dodge. Secondly it has large sharp powerful teeth, which could be represented by a claw but their actual claws are closer to that of a dog, for digging.
They also have much more power to bound than humans, and a shape that lends that power to singular sudden acts, like jumping or kicking or lunging. to me that could be represented by Proficiency, because of the strength, Slay because of putting it all into one sudden movement, or Assassinate as it would likely be a surprise to the receiver, much like it would surprise a fox to be kicked in the head. Another thing they have is fur, and being out door animals, particularly northern hares like the whit tailed jackrabbit, they can handle the cold quite well, therefor resist elements, cold, and possibly fire, as they have been known to run through grass fires rather than away from them. Resist magic is a maybe cus well, rabbits feet are lucky right? and a wilder kin would have two of them.
I really wish we had a list of established precedents, because the only one with assassinate is the sar, and they have it because of their amazonian culture, not because they are tiger kin, to which slay or proficiency would be more accurate.
Anyway, that's my rebuttal. it may not convince you but i hope you at least concede that they are good arguments.
Cheers