These accounts can't normally be attested to through scientific testing.
Wrong. Just watch history channel. We know a lot more of historical events than just the historical accounts. Archaeology is making huge discoveries about historical events. A prime example is the archaeological work that has been done over the last 30 years at the Battle of Little Bighorn.
Archaeology, history, and Custer's last battle: the Little Big Horn reexaminedArchaeological Persectives on the Battle of the Little Bighorn
This research drastically changed what we thought we knew about a lot of the Little Bighorn Battle. Also, through scientific inquiry(archival science), unknown accounts of the Battle have surfaced in the last 50 years. Scientifically we can show that there is a reason to believe that they are actual accounts from actual participants. Through scientific analysis we also have been able to relook at the native accounts and see that they are much more accurate than they were given credence for during the first 100 years after the battle.
The Last Stand: Custer, Sitting Bull, and the Battle of the Little Bighorn
The study of history is much more than reading accounts. Please do not belittle that which you know little about. The study of history is a multidisciplinary field that relies extensively on science in order to determine as close as possible the historical "facts".
Facts don't lie or have an agenda. Facts are just facts