I hadn't heard of the Mesa, because of your post I went and looked them up on line. You do need one! Because you have a 119, the ultimate Buck fixed blade (you do have a Buck 119, right?). The Mesa is cheap enough and has a sturdier blade shape to let you do abusive stuff that you don't want to do with your lovely 119. Oh wait, you have a Buck 105. So you really need a Buck 119 and a Buck Mesa.
The 119 is your BMW, skin large game and debone whole turkeys with it. The 105 can help out. The 105 is for wearing when you go small game hunting in a sports coat, carrying a 28 gauge double. I hope the grip is made from some exotic wood.
The Mesa is your old truck. Cut down saplings with it. Cut through the cartilidge of a whole rack of ribs. Heck, cut through the rib bones!
Yeah, you need all of them.