Creating an app that uses WoW Icons

Hi all,
I’m creating a phone app that allows users to compare their WoW Classic character advancement, and creates a ‘ranking’ (of sorts) of the characters.

I use the Blizzard API to retrieve the character information (achievements, mounts, heroic kills, etc) and also to retrieve the character avatars.

I’m also using some of the WoW spell icons (for example the “spell_chargepositive” icon, for adding new characters. The icon is the big blue “+” that you get on Thaddius in Naxx). All in all I use maybe a dozen icons max.

Some of those icons can be fetched via the API, as they come up in the ‘item media’ endpoints.

Am i breaking some copyright law here? I’d assume that we can freely use whatever we get from the API calls, but didn’t find where it is stated.

Any help welcome.