Route: Sandia Knife Edge of the Shield

Park at the Piedra Lisa-South Trailhead and take the Piedra Lisa Trail north. At the ridge, stay right on the Rincon Spur Trail. The trail will end, stay on the ridge until you reach the end of the knife edge then bushwhack straight up (southeast) to the N Crest Trail. Follow the trail south and take La Luz and the Piedra Lisa - La Luz Link Trail back to the original trailhead. 

You can alternatively park at the La Luz trailhead and take the Piedra Lisa - La Luz Link Trail to the Piedra Lisa trailhead to continue the route from there. 

More info can be found at: 

https://www.mountainproject.com/route/106242069/knife-edge