What iceman is saying is correct, ill take the info from the skill calculator.
Demon wave has only a fixed damage, there is no % energy damage component to it. Hence if you have upgrades claws or not the damage should always be 349 at level 4.
We are referring to burn damage, if you use the skill then the blast will hit and cause a fixed damage, then the burn will start its effect but this burn that is supposed to be 133 with 2 sp and 157 with 3 sp, just causes 90 and sometimes even less.
Indeed mobs have burn defense, but serious no matter the claw you use, and the upgrade that you have on it, it always cause less damage than the one in the description, never more.