[quote=Little_ninja]
And I am unsure if there is a way to check which sword skills you have technically unlocked or can use. I am unaware how that works, if they simply activate it and realise or if there is a list or something with requirements to unlock
[/quote]

I can actually help with that. In SAO, most advice, such as new quests, skill prerequisites and rumors, are found through Information Brokers. It was one of my favorite aspects when I watched, the idea that someone can make it through a game just by knowing things, rather than grinding for hours. I assume that the information brokers gather their information by talking with players, NPCs, and checking bulletin boards, so once a player unlocks a skill they can sell the information to a Broker, who will then sell it to someone else.