Gathering dust

This game frustrates me and I’m sure new players will find similar issues. My biggest criticism would be in how the game is limited in the beginning.
If in the event that someone is lucky enough to pull a legendary piece of equipment for a character then they are doomed to watch it gather dust in their inventory for perhaps a month or two or more. I understand that this is likely to create some balance or limitation to encourage a player to level up their characters but surely this can be achieved in a way that is both more fun and less punishing.
To this problem I offer this solution… the introduction of a proficiently system. This would limit the use of items early on but still let you use whatever you happen to have found.
Let’s take for example a sword with a current limitation of being made available at level 10. Instead of locking it out entirely would it not make more sense to create a penalty for using it earlier? I would suggest 10% less damage per character level less than the requirement and perhaps an additional 10% chance of a miss entirely. A character at level 5 using a prerequisite level 10 item would be hitting at half damage with a 50% chance of missing each attack.
They certainly would still be limited but able to enjoy whatever items in thier inventory they’ve found. Simply saying that sword is too complicated for you to understand how to use is not realistic. Trying and failing alot would make more sense.