Trekking poles
Rent for one trek. Buy if you hike at home.
What to look for: Collapsible aluminium, FLIP-lock not twist-lock, carbide tips
Aluminium bends where carbon snaps, and a bent pole still gets you down the hill. Trekkers repeatedly warn off twist-locks, which slip under load, and off ultralight poles that will not hold a grown adult slipping on ice. Descents are the agreed use case — the Thorong La descent is the one people name.
Buying beats renting here: a serviceable pair is $5-15 in Thamel or Namche, against about $1/day to rent. Plenty of experienced trekkers use one pole rather than two, purely as a brake going downhill.