I always have a couple of the disposable gas fireplace/campfire/lantern lighters with me.
They need shielding from a high wind, but you can't burn your fingers.
If the line is often going to be fed through a block or a cleat,
I pull back the cover and trim the core an inch short and fuse it tight,
then I push the cover out and fuse it tight.
This puts a slight taper in the tip, which makes it feed easier when rigging.
For a dead end, I just fuse it into a big ball.