Normal people in Naruto don't have such immortality techniques like Oro. And no decent fighter in the series has ever been defeated with kunai, no matter how many were thrown. They are pretty much useless for direct fighting. They seem pretty nice for carrying exploding tags, though.

And I'm not saying a sword would be any universal winner method but it would be highly suitable for fighting someone you otherwise would fight in empty handed melee (taijutsu). Nor is a sword glued into your hand. It doesn't give any disadvantages in that sense. You can even throw it into your opponents face to momentarily confuse him. However, when somebody attacks you empty handed and you have a sword in your hand, it gives two definite advantages: Reach and cutting damage (bleeding will weaken the opponent). Plus it's of course intimidating.

But when fighting some of the monsters in the Naruto world, a simple sword surely isn't enough. But of course a sword doesn't need to be a simple one. There could be any number of chakra based techniques used to enhance its abilities.