The best way to make an object symmetric is to cut it in half, copy the layer, and mirror it. This may not work so wonderfully here, as the pommel shoots so far off to the side; it would make the bottom of the grip and pommel wider than the rest of the sword's handle area. If you were only to work more on this in digital format, you might want to bust out a warp tool to help set the handle a bit more straight.

In the center of the hilt, beneath the halo, you could also consider adding a crest of some sort for even more flair.

For a basic architecture of a sword, [here].

Commenting on it as a weapon, I think it looks like a one-handed sword with a short blade. Extending the grip would make it usable as both as a one-handed or two-handed weapon, and as you extend the handle, why not the blade as well?