Medieval Armor and Weapons

Would chainmail armour be practical here ?

I'm not sure if it's unreasonable.In videos I've seen of tests of arrows against armour the shafts usually break, so that the weight of the shaft does not fully go into the penetration.Stiffer shorter arrows have, therefore, a better chance. Thus the men fighting heavily armoured troops may choose crossbows, which with their long reloading time would literally trade number of shots for heavier shots.

Interesting about heavy armor - can you point me at something to read?

That sounds more like GRRM is writing Syrio as saying their swordfighting is inelegant, not that the weapons themselves are heavy. From what I understand, there was often a lot of hacking and hammering to get through the armor, even if the weapons were light. From here:https://en.wikipedia.org/wiki/Half-sword> Half-sword is used for leverage advantage when wrestling with the swo

Chain mail is usually effective against arrows I believe?

Nothing about a sword being straight and sabre curved?

I recommend to go to a medieval fair, there you can touch and handle melee weapons freely to get an idea how they feel. I remember that I once handled a parade sword which had a very thick and ornate blade, my arms were hurting immediately. Then the guy handed me his own short sword which was used in the fighting demonstrations and it was literally like picking up a can of beans: much lighter weight than expected and I couldn't feel at all the "length" of the blade when I swung it

You wouldn't even bother using swords in a battle of plate wearers. Simply too ineffective. That's when they'd use the knightly pollaxe. Now that'll do the job.

Pioneers always design armour where there _weren't_ arrows before?

Well actually against modern armor they wouldn't work much better than nothing