I've been wondering... in the 5.3 patch art we see the Exarch holding a crystal of light, which is entirely different to the ones we see him experimenting with in the cutscene before.

Just a thought but it might be interesting if we have to use the WoL's crystals of light to take the Scions back - we have six of them, so five for the Scions and the sixth for the Exarch's memories... it might also leave us in an interesting situation power-wise before the "final battle" so to speak. Probably nothing but I thought it was interesting to think about.