hehe, if the blade wasn't hand finished originally (ie was polished with a grinder), which is the way most production knives come,
you probably wrecked the blade finish. Shoulda just left the scratch! I guess what you COULD do, which isn't too hard actually, is to hand polish the entire blade. This isn't as hard as it sounds! Especially since your tanto (what knife is it exactly? brand, model name?) is probably flat ground. Probably you'll have to take the knife apart (it's a folder?), and start sanding with 320 grit or so, to remove the old scratches, sand in ONE direction, horizontal to the blade at first. Then move up to 400, sanding at 45 degrees, then 600, rotated 45 degrees again.
should give you a good satin finish. Course, if you've never done this before, maybe your better off leaving it alone. Or maybe my post is too confusing and someone else can give better help?
Jadis