Cepheus Daidalos is an A-rank Saint with the ability to steal enemy attack power, which gives him a clear support niche. Spiritual Chain - Black drains part of a target's offensive stats, and Spiritual Chain - Holy can transfer that stolen power to one ally, effectively weakening one side while boosting your main carry. For early PvE progression and fresh accounts, this can still be a practical way to stabilize damage checks.
Unfortunately, he is a unit from the early era of the game, and modern rosters offer many stronger supports with better utility, consistency, and tempo. His value drops significantly in higher-end content, where the opportunity cost of running him is too high. He definitely had his moment, including older Jamir seasons, but today he is more of a transitional pick than a long-term core unit.