I agree. A libertarian army is likely to prefer weapons that severely limt or eliminate collateral damage.
This is one reason why a libertarian society is unlikely to produce, much less use, nuclear bombs, which from the standpoint of the NAP are the greatest possible evil, constituting the maximum number of aggressions per second via collateral damage to innocents.
Tactical nukes might be a different story however, those can be limited to field of battle with perhaps only a few kilotons going off.
A libertarian army might greatly prefer lasers as weapons, for these truly can be well limited. You could take out one aggressor in a crowd with a laser, from the air, and be assured a kill while also having high likelihood of harming no one else in the process. By such means terrorist bombers, for instance, could be eliminated, even while trying to use human shield.
I think the American military drive towards decreasing collateral damage is a positive one, but clearly there’s a ways to go. Ancient armies simply didn’t give a damn. We’ve progressed as a society a bit in that regard, but clearly not enough.