An update. I've decided to take up John's extremely generous offer on the Warring States Period Tanto. Thanks so much John, you are an absolute pleasure to do business with and extremely honest too, explaining in great detail exactly what the item is, and all the pros and cons. Thank you.
Also, a thank you for all the members who offered their advice. I, admittedly, walked into this with an attitude of purchasing the handles anyway, but after your honest opinions I was drawn in, and now am the proud owner of a genuine Tanto (after receiving and doing more research myself i'll try to upload some pictures and make a post about it). And that will, hopefully, be a gateway purchase into the broader world of Japanese sword collecting.
Once again John, thank you so much.