The Sword of Alexander is a Manga/Manhwa/Manhua in english language, GORE series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.nl fastest updating comic site. The Summary is

Yorozu Genkurou, wandering warrior, possesses a huge sword which makes him redoubtable to his enemies. While he crosses a dark forest, he suddenly sees the fall of what looks very much like a spaceship. Since, he is constantly being attacked by strange ninjas and ambitious fighters. Indeed, he will soon realize that his assailants are nothing else than aliens landed on Earth to find 3 artifacts made of Orichalcum, an alien substance with powerful mystical virtues. And one of the artifacts is the sword he wears. The hunt begins.