This is a quick guide for someone visiting the city centre quickly, wanting to get a knife or multitool etc. Feel free to write your own definitive guide to shopping in Stockholm any time you want to do so.
In general Stockholm is expensive, regarding accommodation, shopping, food. People living there must be loaded.
People are generally friendly and helpful.
For various Fällkniven (I do not buy them, for personal reasons) some EKA, some Morakniv, some local makers and various Buck you can go to Walter Borg AB, a (extensive) hunting/outdoor shop that does have a decent selection of knives and some multitools. It is very close to the main shopping centre and the central train station. The Swedish knives are at good prices, surprisingly for Stockholm. I included a photograph of their knife display. They do have some nice hunting knives
https://www.google.com/maps/place/Walter+Borg+AB/@59.3340422,18.0576138,3a,75y,90t/data=!3m8!1e2!3m6!1sAF1QipNSzQpSC0NTzvpA_iVZnP_hVInsw0uXiyDwasYv!2e10!3e12!6shttps:%2F%2Flh5.googleusercontent.com%2Fp%2FAF1QipNSzQpSC0NTzvpA_iVZnP_hVInsw0uXiyDwasYv%3Dw152-h86-k-no!7i4032!8i2268!4m5!3m4!1s0x465f9d60d4ba1115:0x4aceef413ec20d19!8m2!3d59.3339846!4d18.0576691The staff is friendly and helpful, which let me to buying two knives...
There are also some kitchen/housewares shops near the centre e.g.
https://www.google.com/maps/place/Cordon+Bleu/@59.3341318,18.0561445,3a,75y,90t/data=!3m8!1e2!3m6!1sAF1QipOi2uTKISmaJIiwAEHdq7sGYXqgVnZeNTFP0u0N!2e10!3e12!6shttps:%2F%2Flh5.googleusercontent.com%2Fp%2FAF1QipOi2uTKISmaJIiwAEHdq7sGYXqgVnZeNTFP0u0N%3Dw114-h86-k-no!7i4032!8i3024!4m5!3m4!1s0x465f9d66d31ca971:0x1a1d3d450b71e515!8m2!3d59.334185!4d18.056381where you can buy various kitchen knives, some opinel knives, some victorinox..
In the old city centre their are some tourist shops selling Scandinavian knives, of touristic quality - photograph included.
You can also find cheap no name multitools in Tourist shops, with Sweden engraved on them.
Enjoy.