Why is a well aimed bullet more humane than a poorly aimed one?
A quick death does not equate to humane, as anything used to kill is in effect, inhumane as it is used to destroy a human. I cant see how any weapon, regardless of the quickness of death can be humane. Look at the struggle with executions to find a painless and humane way of killing. The seemingly only humane way to kill would seem to be via lethal injection that educes a sleep-like coma followed by death.
At the end of the day we cant ask people how it feels to be killed by this or that as they are dead.
It is more a case of which form of killing is more socially acceptable to us, but this depends on your culture, religion and upbringing.
For example, in Nepal or Tibet, I forget which, human bodies are sent into the afterlife by being chopped up and fed to the birds... hard to bury in mountains and not enough wood to burn the bodies. This would seem repulsive to those who have to have the body whole to pass into the afterlife.
Its all a matter of perspective but a weapon, of any description has to be inhumane, otherwise it would be of no use. It is used for the destruction or injuring of humanity, and is per se inhumane.
What is a humane sword or rifle?
Thats my philosopy rant over with...
But if I got pick a 'nasty' weapon it would be one of the 'flame' variety... or a chemical or biological agent... yuk! Dirty war!