So the general way the world seems built is you awaken to a class on some particular age, which shows in the form of a tattoo on your hand. MC awakens to a blank tattoo and is ostracized for being classless, but it turns out he is not only 1 of the rare people with more than 1 class, but he has 4 of them and he can pick and chose exactly which ones he wants, including super rare ones. The only class I remember him having is bladedancer. MC fights dual wielding for some reason, gets taught by an assassin woman in the forest after the first (?) act which involves a city that either gets invaded or destroyed for some reason. It was a pretty good book, but I can't seem to find it or Google. Think the book was on royalroad, but it could be kindle.
I don't know what you looking for but if it crest i remember read "Shikkaku Mon No Saikyou Kenja" and if it classless maybe "The Hero Who Has No Class. I Don't Need Any Skills, It's Okay/Mushoku no Eiyuu: Betsu ni Skill Nanka Iranakattan daga" Sorry if that wrong