{last word} can it be redirected with {swerve} onto itself
No because 1. I'm not sure if that's possible and 2. it is not a legal target for any counters.
No, a counter cannot legally target itself. However, you could change the target of {Last Word} to {Swerve} itself. That way, swerve resolves, last word fizzles for lack of a legal target.
Confirmed.
It just says last word can't be countered, maybe you could change the target to itself and it wouldn't be countered but wouldn't counter anything else cause the target has been changed?
*edit: ahh okay can't target itself.