There are various other systems to increase your character's damage abilities outside of Equipment.
Gain experience to increase your Hongmoon Level. Each Hongmoon Level will unlock additional Hongmoon Points for you to increase stats freely! To access this feature, press P.
Complete Achievements to unlock Skill Enhancement Points, increasing the base damage of your main skills.
Bonus Attribute serves to grant additional stat increases from completing Achievements.
Unity, an account-wide Rank system opened by pressing CTRL+H, will increase all of your character's attributes. After starting at Rank 1, each Rank will earn you special benefits such as HP, Defense, and Critical Rate. You can increase your Rank up to Rank 180. To increase your Rank, you must gain Reputation.
Equipping an Amulet onto your weapon can grant you additional stats and Skill Enhancement Points.
Upgrade your equipment to the Mythical stage using the Mythical Enchancement system.