Trent,
I'll concede that animals have "weapons" evolved to use against one another. I'll even add that if you use a firearm to defend yourself against a non-human attacker with teeth, claws, hooves, etc., then that firearm is serving a self defense role and therefore a "weapon" role.
However, browsers, grazers, and animals classified as varmints don't usually attack humans. When they do, it's because they're diseased (rabid) or because they feel threatened by that human, in which case they are simply defending themselves.
The first definition in Post 40 clearly means "by humans" and implies against humans as it includes a list of implements. Very few animals use implements, and those that do have generally not weaponized them.