On ‎7‎/‎12‎/‎2019 at 4:53 PM, Sir13scott said:

When Finn Defends he can take the strain to add the focus to his already rolled 2 dice, and then after resolving the attack you may remove the strain. As long as you have a focus why not? If you don’t have a focus, the blank might get you a heroic trigger.

When he attacks he has to keep the strain if he added a focus, but if you don’t have a focus you can again try and re-roll the blank.

This. With Heroic, on the defence the blank could actually be just as good as the focus, so in practice it's not a big deal for them to be the same cost.