Feeding New Skills Into the Mesh
Eren kept rummaging through his Spectral Screen, trying to know the essential stuff.
He found out that the category Profession was closely associated with one's identity in Labh Salem. It was something that almost nobody could change once they had made their decisions. At least not on the fly.
Plus, those who used Menaka's Blessing could only use one Profession at a time. If they somehow managed to change their Profession, the progress they made in their previous Profession was practically lost.
Of course, there were exceptions to this rule in the form of rare items, artifacts, and certain Perks that one could buy from Menaka's Market, etc. However, nobody else was as spoiled for choices as Eren was in this department.