Is there a difference between "Hero has first strike ability" and "Hero gains first strike ability"? Are both of them "gained" abilities that would leave battle if the hero they were given to was forced out of battle (a choose the rescuer card, for example)?
Since they say "Hero gains/has first strike ability", do you have to apply the first strike ability to the hero the enhancement is played on, or could you apply it to another hero? A lot of the set-asides use similar wording (Set hero aside) and their effect can be directed to a different hero.
