Well a lot of today's historians disagree with a lot of yesteryear's historians so who's "facts" are right?
Mark
While history is not as solid a science as the hard sciences, you still have to be able to back up a theory--or opinion, as we've called it--with arguments based on facts.
Admittedly, we can look at the known information and come up with a new way of explaining it. Or new information can come to light, that does overturn previous ways of looking at things. The example of the Battle of Midway comes to mind, and the work of John Lindstrom, and Parshall & Tully. They took Japanese sources that were hitherto unknown to Western scholars, and they have revised the interpretation or understanding of the battle.
However, in both of these specific cases, the challenges don't seem to have much of a leg to stand on. In the case of Hitler's fate, there has been no concrete evidence to disprove the "official" story that he shot himself, that his remains were partially burned in a shell hole in the Chancellery garden, and that they were later found by the Russians. In the case of the sword, you're right, it will be interesting to see what archaeologists and experts on Roman history have to say, but right now, it's speculation on the thinnest of threads to posit a galley cruising along the North American coast and trading with the ancestors of the tribes who met our European forefathers when they came much later. That speculation can be fun, too, but we should not confuse it with actual history.
And that is precisely what the History Channel does, for ratings.
Prost!
Brad