Anyway, here's my list of ten weapons that changed the world (in no particular order)

#1. Bow and arrow (ancient design)
#2. Gladius (sword)
#3. Medieval siege weaponry (particularly the trebuchet)
#4. Matchlock weapon (first practical mass-produced small arm)
#5. Gunpowder artillery (particularly naval artillery)
#6. Rifled, breech-loading long arm firing an all-in-one cartridge (Henry repeater)
#7. The machine gun (Maxim, Hotchkiss, Vickers, etc.)
#8. The airplane (Fokker Eindekker E.I)
#9. The assault rifle (Shturmgewher 44/AK-47)
#10. Atomic-based weaponry (fission bomb, fusion bomb, thermonuclear device, etc.)

The 11th weapon will, of course, be the first viable laser rifle. Currently under development by any sane military R&D office.

I thought about attempting to squeeze guided munitions into the list somewhere, but everyone who has ever played a "conquer the world"-type RTS knows that airstrikes and air combat alone does not a successful military campaign make. Boots on the ground in sufficient numbers are what wins battles, and therefore, wars, and they have to be armed with the kind of world-changing weaponry that this list represents.