Estimating age on an itak

[blindside]

Any suggestions or rough guidelines on what are indicators of age on Luzon pieces? I recently picked up this through our local Craigslist, it certainly isn't a high end piece, but I am curious how one would go about estimating an age.

The guard isn't aluminum, it has a faint bronze tinge to it, something that I haven't seen before. Any suggestions would be appreciated, thank you.