Glue, solder, or a precious metal. I still don’t think it would work, though.

The khopesh (closest thing you’ll see to a Dothraki arakh) wasn’t steel, when it was in use, and it wasn’t used against heavily armored opponents. It was handy for slashing an opponent while one was in a chariot and moving at a good pace. Scimitars and samshirs operate on a similar principle, using a single edge for greater efficacy when riding past an opponent to slash at them or their mount.