Cognsiscent characters in my Amalgam Universe do not fly, but they can glide. Some have truly vestigial wings owing to avian heritage. They're still... "wings" based on the Walks Like A Duck principal even though they're functionally arms.

So something like a sling that serves the same function to support an injured arm even though it's rigged differently is still called a sling. Regardless of how the body is arranged.