Occasional blood here and there. Mainly towards the end.
PG-13 material - Arthur stabs an enemy then slices he's throat, blood sprays out and blood can be seen on his neck (Probably the most brutal death in the film)
PG-13 material - A scene in Morgana's lair, we can see a prisoner that she has tortured. His eyes are cut out and are wrapped with a white cloth reviling two blood stains where his eyes used to be. This can be graphic, but it's in the background.
Borderline PG-13 - A villain is stabbed twice on screen and is killed, the first time they are stabbed blood is shown. It is very dark blood and can only be seen for a slit second but still visible.
Borderline PG-13 - Arthur breaks an enemies leg then slices them across the chest with his sword, the enemy falls to the ground and is killed. We can see the blood briefly where Arthur sliced him.
An enemy falls on Lance's sword and before they are killed they say, "Thank you."
A wizard and a witch have an intense magic fight.
In the ending battle one of the villagers in the background can be seen getting their throat sliced.
Arthur kills a stick creature by cutting it's head off. The creatures head is hidden while he cuts it off, but Arthur pulls it up on screen. Not graphic.
Gwen fights one of the Guardians with a stick.
Merlin shoots magic and explodes an enemy killing them.
Morgana slaps Mordred a lot, for laughs.