@Pelinal Every bit of his fighting techniques were imitation since the dawn of man. He would have underdeveloped versions of all of those especially 4000 years ago. Then spending 3000 years with mana would make your ability to use the more modern advanced earth techniques worse.
Also mind you, the guy he's fighting is huge. Also mind you, they fuc*** off the planet 4000+ years ago. The oldest martial art is considered to be Kalaripayattu, which was made 3000 years ago. So he would've missed that, and especially would've missed the start of modern martial arts in the 19th and 20th centuries

@Mau He fully said it's because the MC is irresponsible, irreverent and actively makes situations worse through his volatile headstrong nature. Lucifer just thinks he'll be a better leader than him. So he's taking the opportunity to strike while he's gone.