Shadowmoon Knight Oentius is an NPC in the first BLACKSOULS game you can find in the Subterranean Land K’n-Yan area you can get to right after defeating the Lust Demon Satyr and leaving the Entrance into Darkness area.
Oentius is located a little bit to the right in one of the more tucked places, you can easily pass by him on accident without noticing.
He’s a knight who wants to join the Black Trial, but eventually, when he reaches Baphomet, she decides he’s not pure enough and proceeds to kill him on the spot, crushing his hopes and dreams (and life).
I wouldn’t challenge him to a battle personally as he’s quite strong, but killing him will give you one of the strongest weapons in the game – Shadowmoon Blade, its attack increases with the number of sins you have. This is quite nice considering you can buy a lot of sins from Donell in the Tainted Bog, and that can be quite overpowered.
