It looks like an old keris sajen, but the carved features at the base of the blade do not look quite like any i have seen before. Could you post a photo of the entire keris and a clearer and perhaps closer image of the gandik? Does the close-up show an indentation in the blade. Perhaps this keris is also pejetan, though that usual involves more than one indentation.
Judging age on these keris is always difficult. They are sometimes mistakenly referred to as keris majapahit, though most of the ones you see are rarely from the mojopahit period. They are talismanic offering keris and are still made today. Often the new ones are aged and sold as old, but yours appears to have some real age.
Here is a link to other talismanic keris posted on Alan Maisey's website.
http://www.kerisattosanaji.com/kerissajen.html