I've always thought of Rune-master as a form of resource acceleration or at least, being able to essentially play most signal cards for free, but I had a thought when looking at TalesftCards Grimbeorn deck. This card really enables the signal attachments to function as repeatable resource smoothing on top of the buffing or healing that they already do. It's basically like have an Errand-rider in play that's immune to archery damage and can give someone attack/defense/healing/etc at the same time. And isn't limited to sending a resource from your hero to someone elses.
Probably not a groundbreaking use of the card, but still a fun idea I think. If only signals were viable targets for Long Lake Trader, that would get crazy.