Walking/trekking poles provide stability and take some weight off your knees on the steep rocky paths to and from the mountain huts and on the glaciers, especially in descent. Though they have to be carried on the more technical sections where you’ll be using your ice axe, they are nonetheless HIGHLY RECOMMENDED as they really do help with balance on uneven snow or rocky ground. If you've tried them already and don't like them by all means come without, but if you've never tried them most people do find them useful, so it would definitely be worth giving them a go.
Poles are easily found in Chamonix, so if you don't have them already they can easily be picked up on the first morning when you get here. If you do decide to buy before coming however, go for the Black Diamond or Gipron “Flick-Lock” system shown in the photo rather than the more common twist lock system; the Flick-Lock system is much more reliable and will not freeze up and lock the pole in the extended position.
Suitable models: any using the Flick-Lock sytem, e.g. Black Diamond or Gipron.