User blog comment:Piyush Banerjee/Shin DxD 2 discussion/@comment-38501836-20190409061954/@comment-2601:87:8300:20D0:4942:5759:4BC3:64D9-20190409151958

You shouldn't over think it for example you can say sealing techniques would be better for Bishop class and Koneko can use them. This may be confusing,  but magic or a type of energy or power can be the same and different from your class. It doesn't make you weaker and to simplify Bishop boosts magic (energy or power), Knight boost speed, but speed can be enhanced with magical or physical abilities and the Rook boost your physical strength for close combat and defense physical and magically such as barriers. The class doesn't restrict you such as just because your not a Bishop your magic won't increase, same the speed of a Knight and the strength of a Rook. In the series they trained themselves. In a way the class is just a boost which probably makes everything I said confusing but there you go.