So I guess this is the manga that makes me sign up, huh?
On the HEMA, for heavy combat, my club does not take it as one hit = one point, rather you have to 'overwhelm' the opponent. The idea behind it is that in heavy armour, hitting just anywhere won't kill, so only hits where there is no armour count. Which is kind of difficult to get unless the opponent is on the floor, so... to be specific, hits between the gorget and the helmet, and at the armpit are instant kills.
Also, there's a stance with the longsword specifically against heavily armoured opponents, but you basically use it as a blunt weapon.
Also, not all 'medieval combat research' clubs do heavy armour. If you just want to train with the weapons you would need much less gear, especially with certain weapons like a rapier. If anyone is interested, it's easy to find clubs. Helpful search terms are HEMA, SCA or 'period combat'.
On the manga, I hope the fights won't go more absurd than this, but looking forward to it.