A friend of mine wrote this and though it's mostly about homerules adjustments to GURPS' combat system to adjust it to these techniques, I find the blog post(and specifically the videos included) very interesting in regard to actual combat technique used in western martial arts for armored combat during the medieval eras.

Case in point the "half-sword" technique(one hand on the handle, and one on the blade to used to sword akin to a short spear to strike gaps in the opponent's armor or use the pommel to strike at his head and so on.

Though, for me the "battering point" technique(also historically used, apparently) was a new one for me, where someone goes to hold their blade with two hands and instead used the guard and pommel akin to a mace to stun and imbalance their armored opponent as well as causing concussion through the helm and armor from the impact of the blows.

For the whole thing, you can click here. While a lot of the text include mostly refferences to GURPS rules(this -is- a GURPS related blog) it however had plenty of videos and images demonstrating the forementionned techniques:

http://jetgurps.blogspot.ca/2014/05/naked-steel-and-ambition-part-1.html

Edit: Updated link at friend's request due to an update they had to carry!