Back in RPGH, the limit of number of ability and weapon slots was quite limited and it depended on your Rank. I don't think it should be that way for this site. This is why I propose that the max capacity of slots is 12 for both abilities and weapons, being 5 spells equal to 1 ability.
No one will need to rank up to unlock this max capacity. Yet, some sort of requirement might be added latter. Yet, it will not require the affiliation of your character with any organization or group at all.