If you have an excellent weapon with 1 option, you can add a Jewel of Excellent Weapon +2 to add another option. You can't use +3 or +4 until you have the right number of excellent stats. So if you have 2 excellent stats, you can only use +3, if you have 3 stats, only +4 and so on.It just adds 1 stat to your item. However, if you have a non excellent weapon you can only use Jewel of excellent weapon +1 to make it excellent with one stat. After that you can use the rest of the jewels.