If you try to create a rosewood blowpipe with the fletching knife, your character just stands there and idles. I guess this interaction wasn't thought of and doesn't work? As soon as I take a knife instead, it works.
#Fletching knife & Blowpipe bug
leaden parcel
ancient brook
It says "Nothing interesting happens" when you do it. I submitted bug report about it the other week. It's kinda annoying fletching knife doesn't substitute the knife in every situation, I get it's a 'fletching' knife but it's annoying that I have to store 2 different knifes in my bank