I understand the stance against signs like
"Trespassers will be shot.... survivors will be shot again"
because it honestly does infer a ready willingness to shoot a trespasser, and does not address the fact that some trespassers are just people who are lost/confused/wrong/stupid, and don't mean you any harm, nor should they be shot....
But "Protected by Smith and Wesson".... well, that only says (indeed warns) that you have firearms... it doesn't imply that you will shoot anyone who steps on your property... in fact, it could be easily argued that this was a deterrent specifically because you DIDN'T want to have to shoot someone....
Go ahead, lets 'armchair trial' this one and see whether the defense is better with "This was a WARNING", or the prosecution with "This was a threat from a madman"
This comes up often enough that maybe we should have signs printed up that say
"I don't want to have to shoot anyone, but I will if I have to."... printed in the 5 most common languages of your area.....