If you are in the field and do not wish to be caught by lighting a fire (sorry if anyone has already posted this but I am in a rush) You made your Drammach( oatmeal and cold burn water or blood sometimes). Not to tasty but it kept skin and bones together!

I have always heard of flasks being carrried although contents varied (probably whisky,whisky, and more whisky) I would imagine they would have been made of boiled leather somehow. I have even herad of stone drinking vessels? Your Dirk of course maybe other weapons...... I can't think of much else in the way of necessity. Maybe a fishing rod or a walking cane of some kind or your pipes (that is what I'd bring, I never leave home without them) In tose days before gortex the pipes had to be played and played often (almost daily) to keep the seasoning and the reeds in good order.

Hope this answers your question!