Hi. Back in your Animation Events, something like this should be about what you describe:
+ Player: is walking
-> Anakin: Set animation to "Walking"
-> Anakin: Set animation speed to 20
+ System: Else
+ Anakin: [negated] Anakin: Animation "Lightsaber" is playing
-> Anakin: Set animation to "Idle"
+ Anakin: Animation "Lightsaber" finished
-> Anakin: Set animation to "Idle" <---- added this entire event
Note: These use Construct's "Copy as Text' right-click context menu function, in case you didn't know about that. '+' indicates conditions, grouped together until the '->' that indicates the actions for the event. Changes that I made in bold.
It seems that in order to effectively use the Animation "Whatever" is playing condition, you must change the animation manually as I did in the new event. Even if it's set to play only once, it will be considered still playing until a different animation is set.