Q: If the original Kansho and Bakuya take the stage in the Holy Grail War, as the twin swords reaching the realm of Gods due to the sacrifice of human lives, will they possess powers as Noble Phantasms? Or, since they did not have wielders in the legend, thus cannot become Noble Phantasms?

A: Absolutely without a doubt that they will be true Noble Phantasms. They will be extremely strong anti-monster Noble Phantasms. Rider's ultimate form--Gorgon Lv100, or the extra-dimensional evil god summoned by Gilles, will all be cut down in a single strike.

Fate/complete material III; FAQ, pg. 134