A demon king ever hungry for powerful souls.
The fiercest of creatures can not touch the ferocity that this demon invokes on his enemies. There is but one way that a demon can rule other demons: kill the strongest of their brothers and prove that they are nothing compared to himself. That is what Valens had to do, over, and over again. He had to kill nearly as many demons as he now has under his command before he could be labeled as a king. That is but a taste of what this creature is willing to do to maintain his throne.
Almost his entire life, Valens has used only his bare hands to rip heads off their shoulders. However, that does not mean that he can not wave a sword. On the contrary, he has a tremendously large cleaver that is at his back at all time. He mostly uses it for show, using it to occasionally execute an opposing demon as an example to all. Beyond that, he does indeed have his horns, which he often times uses to display the heads of defeated enemies. His equipment may be minimal, but when you have the power of a god, there is no need to own a gun.
From birth Valens has fought battle after battle. At age 6 he beheaded his father for refusing him a small child's soul to snack on. At age 10 he broke his mother's neck and ripped out her spine when she tried to turn her back on him. At age 16 he killed an elder demon in a fight because the elder demon tried to steal a soul that was rightfully Valens. This is just the beginning to a history of brutal violence that continues to this day. Valens dreams of bathing in an ocean of his enemies' blood and devouring a billion souls in one sitting. If one thing is meant to be clear by looking through the pages of the history of Valens Avarus, it's that there is no one he won't kill in a moments notices if it can satisfy him in any way.