Describe the solution you'd like
In MMOG, there is one almost universal mechanic—consideration (con) coloration.

Usually a ranking from purple->red->yellow->blue->green->gray (or some variant thereof), it limits what can and can't be used by a specific "banding", modifying how items respond in most ways.

For example, setting an iron pickaxe to have the color band from 30 mining to, say, 90 mining.

Below 30 mining it would con as purple (unusable).
This would mean that before 30 mining, it would con as red.
The higher your skill, the more it shifts from purple down to yellow con at the midpoint (60 mining).
As it reaches 90 mining the pickaxe would reach gray con.
The con would affect skill growth. A gray con pickaxe would give no mining skill at all. A red con pickaxe would give bonus skill XP.

Why is this feature needed
It would encourage people to use higher quality gear rather than the same pack of a dozen stone pickaxes they use from the start of the game. It would also stop cheesing options with making lots of easy items to get skills up at higher levels.

Describe alternatives you've considered
Maybe have con affect the stats of the item? So the pickaxe would lose durability and swing slower at red, normal amounts at yellow, and slower at green/gray. Perhaps giving Fortune or such too. This would probably require a new way of setting skills, however.

Additional context
Just realized it was something the mod didn't do that was ubiquitous to MMO games.