Lethal equipment in modern warfare 3 comes with many options including a Throwing Knife or a Bouncing Betty.
Frag
Cookable frag grenade.
Unlocked: Default
Semtex
Timed sticky explosives.
Unlocked: Default
Throwing Knife
Throw it and pick it back up.
Unlocked: Level 5
Bouncing Betty
Launches into the air before detonating.
Unlocked: Level 37
Claymore
Proximity activated explosive mine.
Unlocked: Level 53
C4
Remote detonation explosive.
Unlocked: Level 69