Yes, I understand. You might have started the "My mc is too overpowered. How do i move the plot" phase.

Why would you give MC that power and then take it away? Also that is straight up click bait. Yeah sure he is still op, but he was less when he first arrived. Were you just trying to give him a load out to start with? Then you make up a Bs reason too.

Not gonna lie, that can't be called instant mastery. It could be called advanced learning or near instant mastery. Other than that though the story was decent, had somewhat good character development, and was mildly entertaining for how long it lasted.