Knowledge of Rune Magic:

This story manages action but let's not forget its a fantasy so magic is a trait, in this psychotic world magic is activated at a young age through a rune that is implanted in the body of the host and thus in dire moments an ability is accumulated but anyway our MC(unaware) had his rune taken out at a young age of 4 by his Mother thus hindering his use of any magic making him a plain old King who kills by firing a gun.