Ending Maker - Vol. 1 Ch. 20

[MangaDex]

 

[Kaarme]

If a longsword weighs 1.5kg, he won't be "dragged around" by it. Since he's not fully grown yet, maybe he could use a bit lighter/shorter sword that weighs just over a kilogram. Though that being said, isn't he already level 10? He should be as strong as any grown man.

Maybe this author has only read bullshit sources and believes sword weight starts from 5kg.