are (were?)viking swords steel? did the vikings also stumble onto a way of making steel (in small quanties) long before steel was invented(officially)?

Japanese swords are.

there was an almost religious ritual to making a japanese sword, with something like a 10 year apprentiship. the whole process was secret.

scientist who have now seen and learned the process, realize, that the japanese method of heating, cooling, burying in banked fires (which smoldered rather than burned) created pure carbon, and the whole process resulted in adding that carbon to the iron, and creating steel.

steel, that was stronger and more flexible (on average) than modern steel (since the sword had slightly uneven steel, the back egde of the sword was slightly denser, (and stiffer) and the front edge (cutting edge) was slightly more flexible (and took as a result, an extremely sharp edge).

the japanese forgers didn't know about alloys, they just knew their long intensive process resulted in stronger, sharper swords.

my other obsession