I was up way before dawn this morning and this superstition crossed my mind. 5AM is a good time to think.
So after a little research I found this on where the gifting superstition originated.
IV. Non-Jewish Sources Regarding Gifting Knives
Amongst the non-Jews, the superstition of not gifting knives was very widespread and mention of it precedes the first Jewish source by a few hundred years. However, the reason given for this superstition differs from the explanations recorded in Jewish sources. Non Jewish sources, dating back to the year 1470, explain that if a knife is given as a present, it can “cut up,” or destroy love and friendship.
The earliest non Jewish source to mention the already widespread superstition preceded Rabbi Nachman by over 300 years. The Gospelles of Dystaues records, “he that gyueth [gave] a payre [pair] of knues [knives] ti his lady paramour on newe yeres daye [on new years days] knowe that theyr loue shall ware colde [know[ing] that their love shall become cold [severed]].”[38] In 1578, Peter Bornemisza echoed this belief in his book, On the Temptation of the Devil, as he writes, “one ought not to give one’s financee a knife.”[39] Soon after ,in the year 1611, Francis Davidson in Peotical Rapsodi writes,“a paire of kniues: Fortune doth giue this paire of Kniues to you. To cut the thred of loue if ’t be not true.” [40]
From its earliest source in the year 1470, this belief could be found in many different parts of the world, especially in England and America.[41] Eventually, around the year 1654,[42] this belief extended not only to knives but to any sharp [metal] tool or object as well, such as pins and scissors. Giving sharp objects as gifts, just like knives, was believed to carry danger, and, it appers that people accepted these "prohibitions."[43]
In the year 1707,[44] we find that the non-Jews thought up a solution to the danger of giving sharp items/knife as a present. This solution has been employed by both non-Jews[45] and by many Jews up to present day. [46] Specifically, the solution entails the recipient to give money or an item of value to the giver, in return for the knife. I assume that by giving money to the giver, it is considered as the recipient bought the knife, and the knife loses its status as a gift. There is no danger in buying a knife.
It is interesting to point out that this non Jewish belief is recorded in the general beliefs of the Iraqi Jews. They believed that one should not give his friend a knife as a present [for the reason given by the gentiles]. However, if the recipient gives the giver a minimal amount of money, then it is permitted.[47] I would assume that the Iraqi Jews were influenced by this very popular belief of the non Jews.
Although inconclusive, this widespread superstition of the Gentiles (not to give a knife as a present) may have played a role in the development of the Jewish belief. This claim is not definite; rather an assumption gleaned from the evidence at hand. Hopefully, with ongoing research on this topic, definite evidence will surface and prove the exact origins of this belief, practiced by many Jews.
http://seforim.blogspot.com/2009/09/knife-is-it-dangerous-gift-for-rosh.html