Arcis is the architect of the Arceuus House in Great Kourend. Arcis can be found in the building east of the Arceuus bank. If you have 100% favour and have locked it in, she will be next to the statue of the castle in the middle of Great Kourend instead.
Players must speak to her after gaining 100% favour in the Arceuus House as part of the Architectural Allianceminiquest. She builds the legs, robes, and feet of the statue.