They talk about bad omen. For example, a bad omen is to pass a knife into your hands, to give a watch, if a black cat crosses the road

It's a Russian superstition: not to hand over a knife and not to take it out of another person's hands, otherwise, you'll quarrel with this person. The knife should be placed on a table and only then you may take it. We also don't give knives as a gift for the same reason.

It's kind of an old superstition about knives. When you give a knife to someone you give them your power and they get a possibility to kill you. So if you want to present a knife to someone, you give it and that person should give you some coin back as if they are buying it. And people shouldn't pass the knife to each other directly according to this superstition. One puts the knife on a surface and the other one takes it as if they found it.

https://yadi.sk/i/Q_cHkyYb5_Ln2g 02:39