Realm of Worlds: I, the Knight, Conquer All Worlds

When he was twelve, his parents were killed by nobles, and his younger sister was taken away by a mage.

Kneeling before their graves, he swore: He would grow stronger, find his sister, and make his enemies pay.

No golden finger, no old man to guide him. His talent was mediocre, and his birth lowly. All he could rely on were his eyes and his life: watching for every opening in his opponents' defenses, enduring every defeat, then getting back up.

From a sledgehammer in a supply convoy to the Blood Ring of another world, from a cannon fodder commoner to the ruler of the Holy Temple.

This is the story of a commoner who fought for everything with his life.

The world is unfair. But he will make it fair.

(It's genuinely well written. Why not give it a try? The first three chapters are just an introduction, so skip straight to the rest if you prefer.)