When the weather is fine, it is very light, with little provisions and something to drink. In bad weather, the paths could become muddy and slippery. So then non-slip shoes and hiking poles would be advisable. Otherwise, you need a warm outerwear, temperatures around freezing are normal even in the summer of the southern hemisphere. When the sun is shining this is a top highlight in Peru.
Don't forget your passport - at the top (roughly where my profile photo was taken) there is a stamp for a few soles. Of course I didn't have mine with me - it still annoys me today.👎🙁