Real slansin respawned again by the time I logged on this morning, ~8 hours after the previous one.
http://everquest.allakhazam.com/db/q...00473769830566 is probably the best post on the topic, but the whole thread of comments from zam is basically full of people saying that they can spawn slansins on demand with the "I study enchantment" phrase, and that you are supposed to be able to keep completing the quest with the real slansin and respawning via trigger phrase until you pop the fake slansin for factioning.