The buff description mentions that it affects close range attacks and magic attacks so it’s 99,99% not a bug. Here a screenshot from what it says:
From the Ignas’ wrath buff experience we can deduce that if we can trust something, it’s the description of the buff itself when applied and not the actual skill/item description in such cases [which says by the way: “[…] adds Fire property damage to your close-range magic attacks”;
I bet the “and” between “close-range” and “magic attacks” was lost in translation xD].
It’s sad that the effect only applies fully to magic circles,though, and it scales only with skill level and attribute level and not with any base stat, which makes the buff inferior to basically all other buffs out there that can be additionally enhanced with e.g. INT/SPR/DEX/whatever stat.
This leaves Aukuras level 15 with max enhancement attribute at 1200 fire property damage for magic circles and at 600 fire property damage for all melee and non-circle magic attacks.