Not to much. Could give her a full sized cuirass+tassets, throw on some pauldrons.



Since she's a fencer though you could be fancy, and just throw the extra armor on her left side. In the 15th and 16th centuries it was considered honorable to do so, as if you were fighting the enemy only your forward (armored) side would be presented to the enemy to attack. If you were hit where you didn't have armor, that meant you were running away.