I don't imagine that the real gunblades were the most viable weapons myself but if improvements were allowed to be made overtime they could have managed to make it work. Bayonetes are the only examples of gunblade-like weapons that are fully functional with awesome real world applications and potential. Heck the modern military forces still use them to this day. The issue with the other gunblade designs is that vibration from firing the gun would vibrate the blade and cause temporary heat at the same time which would lead to morphing the blade overtime nullifying it's use.