Swords used to (e.g. in 1.2.5) break blocks twice as fast as your hand. This only worked on blocks that could be harvested without a tool, and still caused 2 points of damage to the sword (as was normal for breaking a block with the wrong tool).
This no longer happens.
Since it wasn't mentioned in any changelog, I assume this is a bug, and not an intentional change.
Linked issues
Comments 2
Perhaps not twice as fast, but noticeably faster.
I counted the number of times the digging sound plays before the block breaks, when breaking certain blocks in 1.2.5 and 1.5.2.
In 1.2.5:
Plank block: 16 times with fist, 11 times with sword.
Sand block while standing underwater: 20 times with fist, 14 times with sword.
In 1.5.2:
Plank block: 16 times with fist, 16 times with sword.
Sand block while standing underwater: 20 times with fist, 20 times with sword.
Please re-open.
Swords never broke blocks twice as fast as with hand.