Sentinel and Hsien-Ko have been revealed! From now on, I may refer to Hsien-Ko by her Japanese name, Lei Lei, which is easier both to type and to say. Fun fact: Her sister is transformed into the talisman that hangs from her hat. Her name is Mei Ling in the West or Lin Lin in Japan.
Lei Lei's Dark Force mode gives her armor!
Source: Eurogamer (which isn't exactly up and running right now) via iPlaywinner