Augmenting Furniture
Augmenting your Furniture will increase their level.

[Augmenting Furniture]
When you clear a Quest with a piece of Furniture equipped, it will receive Furniture EXP and level up at specific EXP thresholds.
The EXP gained in the Quest will be equally spread among the pieces of Furniture you have equipped.
Example: If you have 3 pieces of Furniture that are not at full level and you obtain 10 Furniture EXP, each of the pieces will receive 3 EXP. The leftover 1 EXP will be lost.