Both dramas are centered around martial arts and have elements of mystery and action as well as some romance. Also, they both have male leads that appear at times to be weaker than the females. If you like martial arts and mystery dramas, but are looking for something a bit shorter than Legend of Fei, Ancient Detective is a good option, because it's interesting, of a similar production quality to Legend of Fei, and could serve as a good in-between show to watch while waiting for the rest of Legend of Fei to premiere.