When I wade in the winter I cover a lot of water. Leaving a backpack on the bank is a pain in the ass because after fishing a run, I'd have to go back and get it before moving on. I used a vest for years and it was ok as long as I didn't pack too much gear. I recently aquired a Filson strap vest. I've only used it once but I think it will be better than a normal vest.
If I'm walking up the trail before daylight I use a small mag light. In addition to that I always keep an even smaller mag light in my pack, sealed in a ziplock bag with a lighter.
My Gerber EZ-out knife is always clipped on my waders.
My .38 is usually in the chest pocket of my waders.
Other stuff that I take:
fingerless gloves
light weight rain jacket
stocking cap
tp
large freezer bag (for eggs if cleaning fish on the river)
water
light snack food

Neoprene sucks for doing a lot of walking. Breathables only for me.