Yeah, I've never had any problem whatsoever with meat; just certain veggies and fruits.
I understand that Jigane is soft to aid sharpening, but is there any good reason for the likes of Shigefusa and Watanabe cladding their blades in an alloy that is so prone to oxidation?
These knives that are iron clad, you mean iron like cast iron like a Lodge cast iron pan or a cast iron Chevy small block? Same kind of iron? Or does it mean a very low carbon, low alloy steel?
I think the latter - very low carbon wrought iron. I think I remember reading that Watanabe uses old chains, but I may be wrong. I'd forgotten about his stainless clad knives - which he only makes in short lengths (up to 180mm iirc)
It's very traditional in Japan to clad woodworking tools in iron and many old long term generational family blacksmiths still do this. Even today it's common for blacksmiths to have an old anchor chain hanging from a tree in the back that they cut pieces off of for material. BTW, the pre-WWII iron is highly sought after for it's higher quality iron ore used in it's production.
As I understand it the slag contained in the wrought iron makes it more malleable to forge, and when heated to forge welding temperatures the slag will melt and act as a flux.
The slag also impedes deeper corrosion, hence it's use for anchor chains.
I seem to remember seeing a shigefusa polished with natural stones which showed up the patterns in the wrought iron, I'll look for a link