I use a tape i got from my roommate who works in the film industry. I'll have to get back to you on what it's actually called. It's like a heavy duty black masking tape that looks quite a bit like leather at a 1:18 scale.
It's pretty simple, you just wrap the sword with the tape sticky side out, then go over with layer of sticky side in. If you wanted to add some stability you could stick a strip of blister plastic (got to use that stuff for something!) in before you do the outside layer.
Hmm, now to add a backpack peg, this is what i came up with off the top of my head:

Hmm, not too shab if i do say so myself, i'll have to give it a try.
The tape also works great for belts and other details, here's a pic of some gear i made for a Ranger custom i'm working on. It's preliminary right now, but it's going in the direction i hoped for:

Black is it's natural colour, but it took that brown paint like they were soulmates. And i'm sorry for the messy pics, i snapped them quickly to post here.
I'll find out about the name of the tape and post it here.