There is no way I can fix it. I tried setting defaults on all magic related items. No luck.
Infamous bugs must be fixed, and ensure it is gone. (I recommend that the particular fixed features must be kept on heavy watch every time changes made to the program are committed.)
That's because once Link has the magic book, the magic sprite uses the book's weapon 3, while the fire sprite is now weapon 1 for the book.
Like I said, it would be a good idea for the developers to add a magic sprite to the item class 'books'.
Oh, my mistake.
I made one fix for this bug (and there has only ever been one fix), but I accidentally miswrote it when getting it to work with the Item Override code.
It is definitely, wonderfully, superlatively fixed now.
(Oh, and the "Fire Sprite" is the sprite for the magic. The sprite for the resultant flame is currently immutable.)
Resetted the defaults in my test quest.
Perfect, fixed in 809. Move directly to exterminated.