Very violent, but nothing a teen can't handle
My 15 and 14 year old sons have both played this game since the launch day, and they both are very into Lord of the Rings, which is why they wanted it so badly. They have other M games, like Halo:MCC or Tom Clancy's Ghost Recon: Wildlands, and they seem to be able to handle the game. The character fights orcs, not humans, and as long as your kid can distinguish between the real and world and fantasy, they should be able to handle it. It is an amazing game!