In reply to exiled_northerner:
I'm not "fast and light", more a beast of burden. Just a personal choice. I carry loads of stuff which isn't regularly necessary. Here are some things which I carry which might fit that category and which you might want to get rid of:
spare socks (one pair for party of two, also serve as spare gloves)
spare hat
cable ties, multitool, duct tape
gps
spare batteries for headtorch / gps
sun cream and midge repellent in the summer
extra food, "just in case"
if I'm cycling and walking in summer I'll carry a midge net because I don't want to be eaten whilst fixing a puncture
a first aid kit which caters for comfort as well as emergency
ski goggles in winter
car keys, wallet, phone in a dry bag
camera
mini tripod for camera
shades in summer
waterproof trousers
spare laces
two man bothy bag
lots of water
As far as crampons and axe go, I use "if in doubt, take them just in case".
All of this is in an indestructible Macpac bag which will outlive me but probably weighs more than some people's entire kit.
My walking partner (Mrs Turdus) carries a steel flask in winter with some soup or stew, in addition to butties. All very civilised and unnecessary.