Some characters use samurai swords, laser arrows, and fan blades to fight monsters on Lyoko. Because Lyoko is a virtual reality computer system, the monsters' deaths are never graphic. They always explode into pieces and then disappear. Sometimes the characters' are unsuccessful in killing the monsters, however, and end up "dying" themselves. This is shown as them slowly disintegrating into white flecks, after which they rematerialize back on Earth. Not at all graphic.
Occassionally, characters are thrown into dangerous situations on Earth. There is very little blood, if any at all. No one ever actually dies, although sometimes characters are shown getting electrocuted, shot with lasers, etc.