If a monster has a combat THEN combat check to defeat, can you reveal the same weapon for the two checks?
Each check is separate, so you may attempt to resolve each using whatever cards you have in your hand. So you could reveal the same weapon for both checks. And since the second check is often more difficult than the first, this is the handy risk assessment of revealing the weapon for the first check, even if the odds of success aren't as great, when you have only one weapon; and then resolving the second check by using the discard or recharge bonus for the weapon, if applicable.