User blog comment:Kogath/Monster Hunter X Discussion/@comment-12049719-20150914112742/@comment-4640052-20150914211926

We may never know if there even was a new weapon planned, they may just have wanted to put one in but did not come up with an idea yet.

Remember the Insect Glaive, concepts for it were everywhere in the old Monster Hunter Illustration books, even with the Kinsect sometimes, but only in MH4 they were able to put it into the game. Personally, I don't think they had a new weapon really planned, I guess they just had the intention of adding one.