BLACK AXE

The protagonist is the immortal wielder of the titular axe, and often referred to by the same name. He’s about fifteen thousand years old, and he’s used a lot of different aliases in that time, but his ‘real’ name (if he has one) and full background are unrevealed. For much of that time he’s been a mercenary, but in the 20th century he retired. And then Mys-Tech offered him one last job