The Elf armor, boots and bracers are sized and designed for an Elf. It isn't that a human or dwarf would be forbidden from using these artifacts, it is a sizing and fit issue.
Human gear is sized for humans, Dwarf gear for Dwarves and Elf Gear is for Elves. Now if you find yourself in a major commerce center that has artisans, then maybe you can get gear from one of the other species. But it will cost you twice the price...
The above reasoning is why the heroes at my table are not presently hoarding the superior Lizardman gear the reptoids use. It isn't that there is some magical reason you can't use the Lizardman gear, are you 9 foot tall with 4 foot wide shoulders that come down in a rapid taper to the hips? Didn't think so...the armor will not fit any heroes. The +4 sword? It is too unwieldy for any heroes. It is far to large and the handle is ergonomically designed with a Liardman warriors hands in mind. Use the sword and risk a wrist injury. Lizardman spears? They are way to large in diameter for the heroes. Once again, this item is designed for a lizardman, thus the spear is much larger and heavier than a human spear. Now it might be useable as a lance or a pike....
~There is one item that the heroes in my game could loot from the lizards and use but none of them want it. "The Nose Ring of Message Spell" {Sometimes this item is a large bone instead of a ring} This item is used as a piercing through the nostril holes of some soldier Lizardmen. When in place the item will allow the casting of a Message Spell 3x per day.
Seems that none of my Players want a huge nose ring or bone through their heroes face.
They have like three of them they never intend on using.~
So it is said that if you know your enemies and know yourself, you can win a hundred battles without a single loss.
If you only know yourself, but not your opponent, you may win or may lose.
If you know neither yourself nor your enemy, you will always endanger yourself.
~Sun Tsu The art of War~