Board Thread:General Discussion/@comment-71.80.99.33-20131014144540/@comment-10104661-20131109235552

Three actually makes sense, for a start, at least. Delphine and Esbern can only train a few at a time. Until the chosen three master their training, no other recruits can be taken on. But yes, once the newbies are ready, they could train a few others of their own, and I would have liked to see this after the main quest and get that army without mods. Yes, the five (or six, if you side with them) total Blades sounds small, but given they survive, their numbers will grow again.