I know this is an old post, but thought I'd contribute to it. Thaidakar is almost definitely Kelsier. RoW says that Thaidakar is off world and can only appear via avatar, Kelsier is bound to Scadrial since he held preservations power. GhostBloods=Kelsier(Ghost) + Heimalurgy(blood magic). Hoid mentions punching him, he punched Kelsier at the well of Ascension.