[HexGirlBestGirl]

Excelgraph may or may not be bugged. But due to the way that tomes work, when dual wielding a better damaging tome than your Excelgraph, you will never cast from it, thus not using the weapon charges for the Excel Crash Benefits.

Considering there's no other case where the usage of tome scaling and auto-selection works, I'm not sure if this is a bug or an oversight.

Ambidex doesn't work and only being cripple armed with my Excelgraph main handed has allowed me to properly cast from it as I desired.