A man murders child, thats an evil murder. A woman who has been abused by a man decides to kill him, both are premeditated so both are murderers so are you saying both should be treated the same.
Abused woman would go down for manslaughter on the grounds of diminished responsibility.
In the case of other murders, why is killing a child considered more evil than killing an adult, if the circumstances are the same?
Take 2 murderers in 2 towns. Both decide they are going to walk up behind the first person they see and stab them in the top of the head with a 12" knife. The first murderer kills a 25 year old man. The second killer kills a 10 year old girl.
Is one killer more evil than the other?