I always burn my fingers on a lighter (I might have had more practice had I been a smoker when I was younger - except I might not be here now to post this ...) and found a very small gas-propelled soldering iron, a bit bigger than a very large ballpoint pen, in my husband's tool box some years ago. He now has to rootle around in my tool box if he wants it. It's perfect for sealing ends and cutting small ropes, with interchangeable heads. I don't know where you get it, but it says "Portasol Technic" on it.
Diana.