The term that best describes segment \( QC \) is angle bisector.
To elaborate, the angle bisector is a line segment that divides an angle into two equal angles. In Arttu's construction, segment \( QC \) is drawn from the vertex \( Q \) to the intersection point \( C \) of the two smaller arcs. Since \( C \) is constructed such that the arcs from points \( A \) and \( B \) are created to intersect inside the angle, segment \( QC \) indeed bisects the angle formed by segments \( QP \) and \( QR \).