It is not often that we are able to really examine and discuss genuinely old Chinese edged weapons, and this piece is especially fascinating. With my own limited knowledge of Asian weapons, I would just like to add some observations, and naturally hope for those of others who study these weapons with more focus.
The patination and age apparant here indeed suggest this sword to be of quite possibly of 17th century, and since Ming attribution is suggested, it is important to note that the northern Ming dynasty fell in 1644 to the Qing (Manchu). The southern Ming did hold out until 1662, but were then overtaken as well.
Since the Ming were the last true Han Chinese to rule, the Chinese deeply resented thier suzerainty to thier foreign overlords, the Manchurian Qing, and throughout that rule (ended 1912) many variations of the ever standing Triad groups sought to overthrow the Qing and restore the Ming power. Naturally this is a simplified perspective that will likely bring forth other detail, but the point is that secret societies have existed in China from as early as 9 AD, and continue to present times.
In the period of the sword we are looking at, one of the main themes of these groups was as noted, to restore true Chinese rule, the Ming.
The sword itself appears to indeed be a very crudely made interpretation of the Chinese jian, and the rudimentary elements of the hilt approximate the pommel and quillon block in most stylized form. As has been suggested, this sword was probably fashioned by a village smith. The most curious thing to me is why would the style of the jian be chosen?
By the end of the Ming dynasty, the jian appears to have become of minor favor as a weapon, with daos with slight curved blades more prevalent militarily (though it is suggested that Ming cavalry are seldom shown with swords).
One secret society that seemed well in place by the end of the 17th century was the Hung Mun (in Cantonese), whose goals were to further religious beliefs and encourage Chinese nationalism. In order to avoid being banned apparantly they took the title Tian Diu Hui (Heaven and Earth Society) , though I am not sure how this would have protected them, in fact many thousands of these individuals were destroyed.
It seems that the jian was used primarily by nobles, and remained more of a dress or court sword (though we know these are entirely deadly...I have seen breathtaking demonstrations by Scott Rodell!). If not mistaken, the jian was also a symbolic item held in great esteem by scholars. In looking at this sword, it seems the blades point is rebated.
Could it be that this sword was rudimentally fashioned to appear the sword of a scholar, possibly in a society such as the name I have mentioned?
I will apologize for the long history 'lesson' ? which is actually my usual trait as most here already know
but it was kinda fun to learn a little on Chinese history and especially put forth some kind of a theory on this extremely fascinating sword.
I hope it will encourage other observations and suggestions!
All best regards,
Jim