dude just kicked a bunch of the terraformars' cousins asses with a stick.
everyone's commenting on his personally change, but i gotta ask:
his stats didn't change in the 3k years he practiced swordsmanship for, yet he his clearly much more dexterous and physically strong (you can't just slice through exoskeleton with a stick without having some level of strength).
unless stats don't actually represent your strenght and is instead a boost? which would be stupid and also disregard the entire premise of his skill at the start
hmmm perhaps they're separate but connected in a way similar to % itd sorta make sense then as the gift weaken him by lowering the stats, kinda like him going from 100% to like 10-20%(considering he said he was weaker than people who never trained or got a gift early on) but then the multiple millennia, of training increases his natural strength making the loss from his gift negligible.
though this early on i'm just spouting random thoughts, but other than "manga logic" it'd have to be something like that or similar since like you said he didnt start gaining actual stats until the monsters, its possible its just from the sword style skill too, it did say something about a boost when using a sword and the stick counts, all speculation for now though lol..