I was pondering initiation Ordeals, when I thought "how about 'Lose Latent Magic Ability' Virtue".
You can either see that as awakening the latent ability, a sacrifice of an unkown potential for known power or ... a ritual that only works for select people ("We must find the Chosen Ones!") 8)
Conversely, I could quite see House Criamon having scripts that grant Latent Magic Ability, in the hope that the initiate will be the source of a new Path.