Crystals should be able to be forged into weapons with other metals to improve durability and increase damage. Crystal arrows should do the most damage in the game with a high chance of the head shattering.
Crystal weapons should be able to be forged with metals to improve their durability and increase the base damage from the metal alone.
Crystal arrows should do as much damage as, if not more than, Valyan arrows but have a fair 1-in-5 or 1-in-7 chance of the crystal head breaking, as the crystal shards are easy to procure.
Personal twist (optional)
Crystals have so much potential for use with weapons, but alternatives should be looked into.