It's not that. If I ever get a chance to work on a game with magical weapons, I'd gladly write a story for each weapon, explaining how it came into the world, but with the normal weapons, no matter how well forged, the options are limited.
Here is the one of the top knife makers, his knives go for 3k and there is a years long waiting list:
His knives are special (I don't own one for the record but I've seen them) not because there is a special little extra, but because the craftsmanship and precision are top notch. The differences between a $100-knife and a $3000-knife are the skills of the maker (40% of the price), the process (completely hand-forged vs stock removal, for example; clay tempering, etc - there's a reason why cheap blades have a fake hamon line; that's another 40%), material and finish (about 20%). Time spent would go into the process. If it takes you two weeks to make a knife, you won't sell it for a 100 bucks. So as you can see, there's very little 'magic' there and very little room for 'he added some notches' unless the story is about how he ruined a good knife.