Code

IEnumerable<ArcSegment> EnumArcs(DiagramLink link)
{
	return VisualTreeHelper.GetDrawing(link).
		Children.OfType<DrawingGroup>().
		SelectMany(g => g.Children).
		OfType<GeometryDrawing>().
		Select(gd => gd.Geometry).
		OfType<PathGeometry>().
		SelectMany(p => p.Figures).
		SelectMany(f => f.Segments).
		OfType<ArcSegment>();
}

private void OnLinkCreated(object sender, LinkEventArgs e)
{
	foreach (var arc in EnumArcs(e.Link))
		Debug.WriteLine(arc.Point);
}