Complex sentence: The primary use seems to be the ability to detect people who contain the DNA of the Minbari prophet Valen who was really Commander Jeffrey Sinclair when he traveled back in time with Babylon 4 to help the Minbari defeat the Shadows in the previous Shadow War.
Split into simpler sentences: The primary use seems to be the ability to detect people who contain the DNA of the Minbari prophet Valen. Valen was really Commander Jeffrey Sinclair after he traveled back in time with Babylon 4 to help the Minbari defeat the Shadows in the previous Shadow War.