The superstition is that you must never give a knife as a gift. You risk cutting the friendship. The tradition is to give, along with the knife, some token amount of money, perhaps a quarter. Then, the receipient gives back the money thus buying the knife from the giver.
In Oriental cultures, it is very wrong to give a knife as a wedding gift. The superstition is that it may cut the marriage. There is no work-around.
And, in some cultures, given a knife is a threat or an indication that you intend to kill the person.