The term "Rostfrei" shows up on a lot of non-German knives too. I see it a lot on Italian knives. Perhaps the word is the same in both languages. I don't know.
I've seen "Rostfrei" on one side, "China" on the other many times. So, don't assume that you just because a knife as some German on it, that it is.
There are companies in Solingen that make cheap blades for folding knives which are stamped "Solingen" (being in Solingen, they're entitled) and then exported, blade only, to usually China or Pakistan where finished knife is assembled around these blades. The factory there then inks "Assembled in China" on with soluable ink or puts on a sticker. This gets it through US customs. Disreputable dealers then remove the stickers or wash the ink off and sell the knives as Solingen German knives. I've seen knives where, with a magnifier and a strong light at just the right angle, I could still read the ink residue on the blade.
Finally, I kick myself for not buying for something like $5, a China cheapie that I saw in a flea market with the blade marked "Rostfrie". My guess is that they made a million of 'em before anyone noticed.
Chuck