It doesn't appear to have been tampered with in that respect and in my opinion to be able to cut steel it would need to be a hard type of steel, and probably 20pts, and not shaped like a regular handsaw, it is very unusual indeed but I am bound to try and find an answer.

I did some investigation on the internet, on Disston saws but to no avail

Maybe someone that speciaqlizes in collecting disston saws or a museum that does--The disston saw company might have some information