I can't believe I'm saying this, but in this poor condition, maybe a little Brasso might bring out a date.
There are probably ways to bring out the date that would permanently damage the coin. I believe the date on some of these is to the right of the 2 at 3 o'clock on the edge. Use a very strong light and a jewelers loupe and you might see a date.
1873-1878 if the imperial eagle on the reverse is the small type and 1904-1916 if it's the large type. Maybe @furryfrog02 will know