I Became a Magic Warrior in my Second Life

In my previous life, I joined a gang and became the most notorious fighter who killed my enemies with knives. Then I died and got reincarnated.
In this life with magic and monster, I have the talent to be both a magician and a warrior. Using the two classes, I will become the strongest. Maybe.
I will try a bit in looking for the reason why I got reincarnated here as well. Because I know that it was my master who taught me how to kill in my past life who reincarnated me into this world.