I was not able to find an etymology of ON "miskunn" within PrG. Is the first syllable a prefix "mis-" indicating any "wrong kunn, lack of kunn" or a deformed "midi-" as in E "com-passion", G "Mit-leid"?
To which root does the word go back? Or did the whole Concept of mercy/Erbarmen first come into Germanic languages with Christianisation? Wulfila translates Gr "οἰκτίρμων" with "bleiþs" (e.g. Lk 6,36) going back on PrG *bliþiz, which seems less pathetic and weaker.