Once you reach the endgame of Lost Ark and collect Gear Score 302 items you will no longer be finding better items off the ground. You will instead use the honing system to upgrade your gear and increase the gear score that way.

Note: This is also frequently referred to as "enchantment" by saying things such as "you are enchanting your gear". However in the western release the direct text will read "honing". And yes, I think enchanting sounds better too :P

Timestamps:
00:00 Intro
00:07 Where To Go
00:18 What Materials Are Used For
00:45 Honing / Upgrade Walkthrough
02:38 Outro