Weapons don't kill people. People kill people.
But strictly from a warring standpoint, I would much prefer a much more humane death via instant incineration from a nuclear explosion or gunshot through the head than getting stoned to death. I would promote weapons development for coming up with "better" ways of killing people.
Now are some weapons manufacturers are also warmongers, perpetuating wars to keep the factories running? Absolutely. And that's not okay.
And do weapons manufacturers overcharge their customers (governments and armies) so they fatten their wallets with tax-payer dollars? Absolutely. The F-35 program is a wonderful example.
Which goes back to the original point, it's people at fault.