Our group used our hiking poles on both the way up and the way down. They help so much when going up a big flight of steps, and on the way down, they save your knees. They just give you a little extra support when you need it.
We all brought our own, but I used REI's Co-op Flash Carbon Trekking Poles and can't recommend them enough! Just make sure you have poles that are easily collapsible so you can strap them to your pack when you don't need them (and pack for traveling to and from Nepal).
Image Source: Caitlin Gallagher