Thank you for your post, Reventlov.
As you can see, thess are the types of Portuguese swords that 'inspired' African natives to produce their own version, like the Mbelle a Lulendo.
In reality, the allusion you might have read about this sword example is that it is the type, or one of the types, depicted in the six panels of São Vicente, a large oil on wood painted by Nuno Gonçalves around 1470-1480.
(you may enlarge this image)
The sword is indeed in the Military Museum and the panels are in the Museum of Antique Art.
Although a more precise style as depicted in the panels is more like this one, a typical Portuguese sword of the third quarter XV cebtury.