Frenzy Rune is an Illusion spell added by the Dragonborn DLC.
It seems to be missing the "Rally Secondary" effect that all Frenzy-type spells inflict onto their targets.
Its tooltip is also not being visually updated by the various Illusion perks that improve what level it can affect.
I do not know does the spell itself properly get affected by every Illusion perk in terms of game mechanics.
Screenshot included.
(also i noticed that the Falmer [Snow Elves] are not affected by Kindred Mage nor by Animage illusion perks, which is weird that they do not belong to any Illusion perk category at all)
Thanks for improving the games we all love!