Here is an Idea thats a bit of a Middle ground between the two extremes people are supporting.
If The item says its "Optimal Used" by like say "Disciples of Land Rank 25" Then only Miners, Botanists and Fisherman over rank 25 can wear it, But they can wear it on ANY class. They already have the requirement They have a DOL at 25, it doesn't have to be active for them to wear it.
If the item says its "Requires" Then the item can only be worn by a Disciple of the Land Rank 25 or higher. So they have to be on say Fisherman rank 25 to wear it.