After day four I used my poles for the first time, and used them every day after that. I liked them even though they were only occasionally useful. Between Muktinath and Ekle Bhatti there was ice in the tire tracks; the poles were useful. Between Ghorepani and Tadapani there was ice and hard packed snow on the many steps; Lal even fell once and my poles often saved me from falling. On these days it would have been nice to have traction devices; it is an open question whether they would have been worth their weight to bring them on the trek. A couple of times during the trek the poles were useful crossing on logs over streams, either extended to maximum length and placed on the stream bottom, or planted on other logs.
I am skeptical of claims that hiking poles improve performance significantly when hiking up hill, because the arms are so much weaker then the legs, and they are at a mechanical disadvantage in the normal position held out from the body. But, I suppose if one has brought them along for other reasons, may as well pump away. One has to do something with them. Sometimes I pump, choreographing the pole plants with the steps of the opposite foot; the concentration required to do this can help the time pass. More often I will use my wrists to plant each pole a few feet ahead, minimizing arm movement and keeping my elbows close to my body, then letting the weight of the pole rest on the ground as it tips forward. That way, I am not wasting energy flailing my arms around, and am not carrying the weight of the poles perhaps 80% of the time! The wrist controlled pole plants can be either choreographed with the feet or not; on smooth trails or on steps it is easier to choreograph them than on irregular terrain.
Lal usually carried my water bottle and down sleeping bag, but his pack was still lighter than mine. One secret of his light pack was he didn’t carry a sleeping bag. In the winter, with so many vacant rooms in the lodges, it is no problem to get extra blankets. I am not sure if he was completely comfortable at the higher lodges like Thorung Pedi. I never had to sleep inside my winter down bag, and only at Thorung Pedi was it necessary to wear my down jacket at night, under the unzipped down bag and a couple of blankets. If I did the Annapurna circuit in winter again, I would take down pants and consider leaving behind the sleeping bag, although I consider the sleeping bag to be almost an essential piece of safety equipment for hiking over Thorung La in winter.
I would take a thermos!