MTL - Great Slaughter System - Chapter 4 Hard choice

Karl Wagner is a disgruntled middle-aged instructor at the Bundeswehr Command and Staff College. He finds himself concerned about the direction which the German nation is headed in—just as he is killed by a terrorist attack. Only to awaken and find himself reborn as an infant, Bruno von Zehntner, the youngest son of a noble family renowned for its part in the German war industry a few years after the founding of the German Empire. Bruno, as he is now known, desires to rewrite history and ensure the German Empire emerges victorious in the coming century. And in doing so, finds himself entrenched in a world filled with Blood and Iron!

In novels with a stud there is always a Senior Martial Brother like this:

In the early stages of the novel, his innate talent is high, his cultivation is good, his appearance is handsome, and he has an intelligent, cute younger Martial Sister as a fiancée.

In the middle stages of the novel, he is caught unprepared and defeated by a young disciple (the protagonist) in the sect who’s hardly remarkable at all. From then on, he falls from his godly altar and loses his brilliance. Even his young Martial Sister leaves him for someone else.

In the late stages of the novel, he continues to turn dark, going down the Demonic Path and becoming the major villainous boss. However, the protagonist still ruthlessly defeats him and his soul is eternally sealed.

Once Qin Mo opened his eyes, he discovered that he had become this Senior Martial Brother.

- Description from Novelupdates

The world’s largest VRMMO, Conviction, was almost like a second world for humanity. It had integrated itself into the real world’s economy, with both corporations and individuals seeking their fortunes through the game.

In this game, Nie Yan prided himself in his Level 180 Thief. He could barely be considered among the top experts in the game. Though, that was the only thing he could take pride in. He was penniless and unable to advance in life; a situation he was forced into by the enemy of his father. If it weren’t for the little money he made by selling off items in Conviction, he would’ve barely been able to eat. In the end, he chose to settle his matters once and for all. He assassinated his father’s enemy. He lay dying shortly after being shot in the pursuit.

However, that wasn’t the end of his story. Instead, he awoke moments later to find that he had reincarnated into his past self. Armed with his experience and knowledge of future events, he sets out to live his life anew.

He was a Martial Arts prodigy, a master of using poisons!He descended the mountain to search for his junior sister but unexpectedly became the School Beauty's bodyguard… From then on, a demon-like student was born! He pursued the School Beauty, took down bullies, and was revered as the supreme ruler of the city! He cultivated Ancient Martial Arts, annihilated formidable enemies, and swept across all directions to ascend to the Peak.