There are a variety of weapons that have both Blast and Breach, or Burn, or any number of qualities. If you trigger both Blast and another quality (or a passive, of course) does it affect the targets affected by Blast? For example, you fire a Flame Projector at a group of Stormtroopers and score one Success, 4 Advantage. You deal 9 damage and trigger both Blast (9 damage) and Burn. That means that all of the Stormtroopers have one health left. Now the Burn quality obviously applies to the original target, but does it apply to the other Stormtroopers as well?
Another example: You throw an Armor Piercing Grenade (13 dam, 3 crit, Blast 4, Pierce 3) at a group of Stormtroopers and score 3 success, 2 advantage. You trigger Blast. The main Target is obviously dead, but what about the others? If pierce applies, then you ignore 3 points of armor and deal 7 damage, killing them, but if it only applies to the original target, you only deal 7 damage to targets with 5 soak, 5 wounds.
Of course you also have concussive and disorient etc. but the examples I gave are the most common ones.