I recall in GMS there was a ring event for new characters that hit level 30 (I think.) The rings provided a boost to atk, matk, a critical hit chance and HP/MP boosts. In GMS the item itself could be traded once within your account. But I think in this case it would make sense to just make it character locked.
It could be interesting to explore adding a unique item such as the above for new accounts only + NX. It won’t stop any current players from opening a new account BUT we wouldn’t be able to use it on any existing high level characters. The allure of an item like this is that it will continue to scale and improve DPS (even for mages through the crit chance) as they shift into mid and late game.
For reference the Adventurer Critical, Cruel and Magical Rings: https://bbb.hidden-street.net/eq/accessories/ring