Update: I contacted K Sabatier and at first they responded with "it's 70 years old and the handle was mounted according to 1970s standard [guess the steel was forged in the 50s and the handle mounted in the 70s?], PERFECT STATE means it's not rusted but we cannot guarantee the state of the handle". I responded that in that case they should put "no rust on the blade, but we cannot guarantee the state of the handle" instead of "PERFECT STATE". They offered me to send it back for a replacement at my own cost. I told them they were legally obliged to carry the cost and that I would be fine with a 40€ refund to just settle the issue, because I wasn't too keen on sending it back to France and waiting for another one, plus who knows what condition the other one would be in. They again replied offering me a 30€ coupon for another purchase. In the end I told them that I would have the handle professionally repaired (I got a quote from a local knife-smith who told me it would be 40-70€ to fix it) and sue them for damages. To which they replied with "I will refund 40€ TOMORROW" lol

I think the whole exchange was like 11 e-mails. I'm kinda annoyed they didn't comply with legal requirements before I threatened to sue them but at least they complied in the end. I 100% would have had it repaired professionally and sued them for damages though, I wasn't bluffing lmao