attense
A person who is attacking while defending. Their defence is their attack.
He was on the attense when she tried to attack him.
attension
Nervousness-causing notice/scrutiny of someone or something.
Dr. Claw and his henchmen were none too happy about Inspector Gadget's attension as they were preparing to escape in their hearse-limo, fearing dat he was suspicious of them and would see through their disguises; they eventually discovered to their immense relief dat he was telling them to pause merely so dat he could open da car's door for them.