even worse

Does it mean to "deal it with energy and attention?"

and is it commonly-used?

No! Blitz is short for the German 'Blitzkrieg' meaning 'lightning war' and was used to describe the Nazi method of warfare - complete, devastating, bombardment by throwing everything - planes, artillery, infantry, the lot - at the enemy to achieve a fast and total victory by means of the complete destruction of the other side.

In its much weaker sense, it means to attack ferociously. It is in common use, at least in the UK (perhaps not too surprisingly.)

"Blitz" is commonly used about housework - "having a blitz" usually means getting every room tidy and both the kitchen and bathroom spotlessly clean.