Blizzard has announced that they are bringing in a new patch that will fix that bug. Patch 1.0.5 will reduce the current value of weapon damage from 1500% to the originally intended 300%.
Lylirra, community manager at Blizzard took to the forums to address why this bug wasn’t fixed earlier:
While this bug was discovered very quickly after 1.0.4 released and is capable of being hotfixed, we didn’t want to move forward with the fix without giving players proper notice. We also know that players are having fun using Trail of Cinders in their builds, so – although this is an important issue we want to address – we’re opting to wait for the next client patch to make any adjustments.
Patch 1.0.5 has no release date as of yet. Blizzard however, has said that it’s release will be soon.