You can hike in snow in sandals (I've done it) but you get very cold feet so it's not a good idea for more than a few minutes! (I was crossing snow neve on a summer hike). On the whole, unless you are doing some serious hiking you don't need anything fancy for winter in Europe - just some warm clothes and decent footwear (something a little sturdier than a pair of trainers, but not much!). Possibly goretex boots might be handy, more because it's often wet than anything.
I like the waterproof document bags made by Quechua, does anyone know who sells this brand in HK?
I have seen similar stuff at HK-China Ferry Terminal's mall, but it is a different design.
Thanks