Aster never trained in using weapons. At most, he would try to replicate movements he had seen on the internet or television before he was frozen in time. However, that method had its limits, and honestly, if not for his stats overpowering his enemies, he would've suffered way earlier than he did.
Facing the Aracelli Race members caused him to realize that he was way too weak. He might have raw stats, but his techniques were below elementary, thus, he's forced into an unfavorable position when facing stronger enemies.
Given these circumstances—and that, as Ardra said, one second in reality is equivalent to a month of training in this weird dimension with the giant moon—there's no reason to refuse!
"Alright," Aster responded, his expression firm and serious. "What should I do?"