Originally Posted by Lance Quazar
Vader doesn't carry a hand-held nuke. Vader only carries a lightsaber. So that's what he used.
I guess he means why didn't they target the rebel flag ship that had the transmission, instead of boarding it and risking people escaping with the plans. I am unsure if the first Death Star is supposed to be capable of targeting a capital ship (It targets cities in Rogue One so maybe its possible), plus its recharge time is much longer than the Death Start II, which could fire again quite quickly. After firing on Scarif, it may have needed time to recharge. Perhaps Tarkin would have been better off firing on the rebel flagship instead of Scarif. I didn't think about it until after the movie, but the Empire must have still had personnel on Scarif, showing their disregard for their own men.