Weapons can be refined by combining a weapon with one of the same type. This increases the potency of the effect of the weapon by approximately 25%. The final refinement level is equal to the sum of the refinement level of the material and the refinement level of the base weapon. The level of the base weapon is the only one maintained. The base weapon determines the cost of refinements, so it is recommended to use lower refinement weapons as the base unless trying to preserve levels.
Weapon Stacking And Ping
Weapons that gain stacks on hit are affected by ping. You will only gain stacks when the hit registers on the server, and the server will process hits at the same time, without caring about when the client actually made the hits.
Freedom Sworn, which gains its buffs from reactions happening, has normal behaviour.
Polar Star behaves differently as it has individual stacks for each type, and will gain all the stacks at the same time when the hit is registered.