>>715888572 (OP)The second sword hurts enemies no matter what, so I'd go with that one.
"Ignores defense" is very vague - so unless OP clarifies that it only ignores *physical* defense, the second sword ignores 50% of *ALL* defense.
Why wouldn't you want a sword that no matter what does at least 50% damage? What if you encounter an enemy that ignores magic damage? Then 50% of your sword's power is gone by default - assuming the enemy doesn't also have conventional armor to absorb the physical damage you'd deal as well.
Sword #1 is worse all-around.