Riddick stabs a man in the head with a knife and then twists the blade, breaking off the handle.
A young woman is killed when she is thrown backward onto a spiked pillar. (No blood)
Not very graphic but pretty intense.
A man uses a tea cup to stab someone in the chest. Very little blood, but the victim falls down dead.
Several men are completely destroyed by extreme temperatures on a fiery planet. The flames erode them down to their skeletons. It is very brief.
Riddick stands atop a manhole cover, while the person below lifts it, searching for him. Riddick then stabs the man in the face with an anchor-like chain. The man later falls hunders of feet down a shaft to his (probable) death. Cheesy, not graphic.