Handles.DrawSolidArc
static function DrawSolidArc(center: Vector3, normal: Vector3, from: Vector3, angle: float, radius: float): void;
static void DrawSolidArc(Vector3 center, Vector3 normal, Vector3 from, float angle, float radius);
static def DrawSolidArc(center as Vector3, normal as Vector3, from as Vector3, angle as float, radius as float) as void
Parameters

center The center of the circle.
normal The normal of the circle.
from The direction of the point on the circumference, relative to the center, where the sector begins.
angle The angle of the sector, in degrees.
radius The radius of the circle

Note: Use HandleUtility.GetHandleSize where you might want to have constant screen-sized handles.
Description

Draw a circular sector (pie piece) in 3D space.


Solid Arc in the Scene View.
	// Create a 180 degrees wire arc with a ScaleValueHandle attached to the disc
	// that lets you modify the "shieldArea" var in the WireArcExample.js
	
	@CustomEditor (SolidArcExample)
	class DrawSolidArc extends Editor {
	    function OnSceneGUI () {
	    	Handles.color = Color(1,1,1,0.2);
	        Handles.DrawSolidArc(target.transform.position, 
	        		target.transform.up, 
	        		-target.transform.right, 
	        		180, 
	        		target.shieldArea);
	        Handles.color = Color.white;
	        target.shieldArea = 
			Handles.ScaleValueHandle(target.shieldArea,
	        				target.transform.position + target.transform.forward*target.shieldArea,
	        				target.transform.rotation,
	        				1,
	        				Handles.ConeCap,
	        				1);
	    }
	}
And the script attached to this Handle:
	// SolidArcExample.js
	
	var shieldArea : float = 5;