Kevin, it is not really safe to judge by photos, but I suspect (left photo, from left to right) No. 2 and 3 and the rightmost are late copies. Right photo: No. 2 and the one rightmost do not look genuine to me. I have seen (and had) a number of YAJIRI, and the authentical Japanese ones were almost always finely and carefully crafted. Their tang is quite finely forged and evenly filed down to a level and smooth surface. As Ian wrote correctly, the copies sometimes have no 'neck' between blade and tang, while their Japanese 'models' do show that feature. This round 'neck' with almost the same diameter as the shaft is an important feature in arrows as the YAJIRI can only penetrate armour and bodies properly, if the impact of the arrow-tip is securely supported and transferred to the shaft. In direct comparison, European arrow-tips are visibly less carefully made (while no less lethal) and were mainly disposable items. The common socket arrow-tip model for warfare was forged in 2 to 3 minutes a piece and often used without additional filing and finishing. But I have to confess that I have not seen hundreds of YAJIRI, so it could well be that there are also mass produced ones which were less carefully made. However, the patina of the arrow's NAKAGO might also be a good indicator for its age (and authenticity).