If you kill someone without "state sanction", as you put it, it's almost certainly Evil.

I think 'almost certain' may be something of an overstatement. The states that we personally live in are not a representative sample of states and killing tyrants is not something we can call 'almost certainly' Evil. The same consideration applies to self defence laws. Self defence laws in an average state selected from all states across time were not sufficiently fair as to make claims about almost certain Evil.