Yeah, I mean those wire saws that come in versions ranging from 'cheap piece of crap that can't pop a balloon' to 'can be used to cut through jail bars' (like the one Chuck Yeager used) quality. There's a gun show this weekend and Dad came up for it. While there ran across a table carrying these:
That's right, it's Commando! and everything! In any case...
No visible teeth to it, it's a braided-wire saw
hooked to two big rings using heavy swivels. Doesn't feel very sharp, so wasn't sure how well it'd work. So, to the yard.
I've got a piece of oak pruned from a tree, about 1.5" diameter and thoroughly seasoned, hard as hell. So clamped it in the vise
hooked my thumbs through the rings and started sawing. It took about three minutes(yes, I forgot to find my watch to time it accurately) to cut through by this method; hooking it to a flexed piece of branch to make a bow saw would probably work a bit faster, but it did indeed slice through.
Second test, had a piece of 1x2 handy, which is a fairly soft wood, and tried it; took maybe 30 seconds to slice through.
So this appears to be a pretty good quality saw for cutting wood, and will coil up small enough to make for easy packing/storage. After I regain strength I'll try to find a piece of metal more suitable for a test than most of what I've got out back and give that a try.
Added: Mattexian noted in comments that it's best to use a branch to make it a bow saw: flex the branch and hook the loops at the ends. In fact, the back of the package shows just that; didn't have anything immediately available that fit the bill so did it the quick & dirty way