Visible textures are always decorative. Japanese handmade knives are always hammered; the finishing, technique, and metals vary. Visual texture = finishing.

do you know if [these designs](https://www.korin.com/HTO-HDGY-210?quantity=1&custcol_korin_addon_items=%257B%2522leftHanded%2522%253A%2522%2522%252C%2522saya%2522%253A%2522%2522%252C%2522freegift%2522%253A%2522%2522%252C%2522premiumgift%2522%253A%2522%2522%252C%2522engraving%2522%253A%2522%2522%257D&custcol_sca_line_id=mainItem%253A7y36pny6x) on the side of knives are purely decorative? or do they somehow illustrate that a knife is stronger than one without them?

Big fan of Korin's chef knives:

https://www.korin.com/japanese-knives/styles/gyuto-chefs-knife

I've had a Togiharu Wa for maybe 15 years now:

https://www.youtube.com/watch?v=hbuuF21oIuM

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I got a cheapo set of 3 Ikea knives that work great, sharpen and great. I know people get all fancy with knives, but I've had these for about 5 years, they

Of course you have to sharpen them regularly. A regular old sharpener is fine.