Raphael had already thought a lot about it before eventually deciding that he was going to take the risk and capture Azekiel. Even if Azekiel claimed that he was more powerful and didn't reveal his strength, Raphael still didn't want to let him escape at this time.
He knew that if Azekiel escaped at a time like this, finding him was going to be really hard. Moreover, if he let Azekiel escape and he really pushed the world into chaos in the future, it was all going to be his responsibility for letting Azekiel leave now.
Just for the future's sake, he wasn't going to let Azekiel leave.
From what he had seen, the fighting skills of Azekiel were pretty good, but they lacked the strength behind them, which made him vulnerable to close range attacks that had more strength behind them.