You can fuse your gear in the Forge to craft equipment of a higher tier.

Add 3 identical gear pieces to the fusion window (same item name and tier) and you will be guaranteed to craft gear of higher tier.

The gear placed in the "Main" fusion slot will transfer its upgrades to the item crafted, however the 2 "Fodder" gear pieces will not transfer anything! Make sure to select your gear carefully before hitting the fuse button!

If some of your gear is Blessed, you will have a chance to obtain a Blessed Gear: