[ufmace]

I'd say the nature of weapons tells a lot about the morality. A gas chamber designed to look like a shower is obviously only useful for murdering masses of helpless and unsuspecting people who are already under your control. I'd be willing to say that's always immoral, no matter the circumstances. A railgun is a weapon, but only really useful against ships and armored buildings or vehicles, and possibly aircraft and missiles. It's mainly for killing armed combatants in disputed areas, and can be used for good or evil. I don't see a moral problem with building them. Like any weapon, they can be used for good or evil, but some lend themselves to one or the other to an extent.