Cheaters ahoy! I bring good news!
It's so easy to make flaming burst available in your game as long as you can live with yourselves for doing so...
Open the TOEE folder, then the data folder, then the rules folder, and then the item creation document (I use notepad).
Scroll down to weapon creation and find flaming burst - it has a C12 in the line that you need to change to C10 and - voila! Your 10th level mage can create a weapon with flaming burst.
You do not need to start a new game or anything!
Thank goodness!
Enjoy!