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These three were the skills Icarus gained when he chose his class, but unlike most skills, he possessed. At the same moment, he was able to use these skills, a flood of information about how to use each of them filled his brain. It's very similar to what happened to him when he fulfilled the requirements and learned the skills
In any case, thanks to this initial understanding, Icarus managed to save a lot of time that would normally have been used to learn. Where he would have to repeatedly use these three skills until he had a general idea of how each of them works