I'm glad you dig it, fella. It seemed so obvious to me that I thought it'd already been made and I'd just slept on it, y'know. In fact it'd be quite a hefty project but you could even extend it beyond its initial premise of "allies thank you" to "actually accurate battle-dialogue reactions", where any NPC may comment on the type of an enemy; for example in the event of encountering a frost troll, a nearby NPC would blurt "blasted frost trolls" or "wow you're a big one" in the case of a giant, etc etc - or even enemies commenting on your appearance (such as your race, gender, build, whatever). It'd take a fair amount of scripting and likely some stitching of voice files together but it seems quite plausible. I know I'd be happy to sift through voice files to find anything appropriate / salvagable if it was ever picked up.