You have Compean's testimony that the smuggler didn't have a weapon (while in the ditch), you have Ramos' testimony that he didn't see a weapon (while the smuggler was in the ditch), and you have the testimony of the other BP agents that Compean and Ramos said nothing of a weapon after they arrived on the scene. So for all practical purposes, there is no weapon, and all this talk of one is only an attempt to muddy the water.
Unless the smuggler had one before he tried to surrender, ditched it, and no one could find it.
I'm not sure why I keep trying, because evidence is just ignored here. I forget what the answer was last time I noted that it was the agents themselves who said there was no gun -- actually, I think that part of my post was ignored, as all evidence that is irrefutable is simply ignored.