Where can I pickup the singing blade? Is it part of a quest? I've heard it's one of the best swords.

I remember for the Singing Blade, I'd pick it up, take it to the nearby trader for identifying and if it had poor stats, reload to just before I picked it up/hovered over it and take it in for id-ing again. That became tiresome so I temporarily added 5 points to the ID skill (with an editor) and kept reloading until the sword had some decent stats. It's incredible just how varied in stats the same items can be. In the end I stopped reloading when it had 4 charm slots, about 30% extra damage, good durability and a few extra damage effects. I think the random variation in weapon stats especially for the special weapons is over done. What's the point in having a rare exotic weapon if in your game it's not even as powerful as a sword you can buy at a trader?

What would be considered some fairly good stats for the singing blade?

I'm not sure there is a "perfect" build for the Singing Blade. It is one of the first swords you find that has high damage (compared to what you find up until then). I think the most important aspect is how many charms your sword has. It can be anywhere from 1 to 5. You can save, kill Pedro, check the sword attributes, reload and kill him again until you get what you want.
(Deleted dupe for re-charming purposes since it no longer works)
It is a good sword weapon, one that I used till the end of game on my first play thru. This time thru, I am looking for comparable Axes, Bows etc for future games . . .=) . . I prefer an axe but have yet to find one with a good recuperation time.
Edit: I tried lightning skill this time, with lvl 4 lighting and the Singing Blade . . . I'm moving right along . . .amazed at how vulnerable Orcs, spiders and zombies are to lightning . . hit them from a distance with lighting . . one whack with the blade . . .=)

Thanks for the advice. How do I dupe my sword?

See the image attached to this post . . .=) . . .Edit : You can still dupe a weapon or armor but you can no longer re-charm)
Edit: Of course, use the sword instead of the potions . . =) . .. . make sure you store the original uncharmed item in a safe place. I use the bin in the abandoned house located in the north-east corner of Aleroth.
If you do use it for potions, I would suggest taking super heals and super magic potions, drop them, in your inventory, on one another, which creates super restores, dupe those. Link to F1 key to the restore potions and each time you will max out your health and magic. It will work with any size heal/magic potion as long as they are both the same size. Might need some Alchemy for that . . . can't remember.

Thanks, Stuff. This should make my game a lot easier.

You're welcome . . .=)