The trail from Arbas to Puerto de Pajares has never been good, and in recent years has gotten worse. Nowadays it is best avoided, and the distance to the mountain pass (1.3km) covered by road. This also gives you the benefit of taking a pause at the bar at the pass.
Church in Arbás is usually open, has a lot of nice romanesque, and has REAL candles for lighting. It requires a 3-4 minute walk off camino, but it’s right there when you get down to the highway.