Swords are light/well balanced, fast moving weapons. Polearms are slightly heavier, head weighted powerful weapons.
A greatsword approximates a lightly balance polearm, and given the choice I would take either the sword or the polearm in preference to an over-large sword.
Full white harness is available, and while wearing such armour you are very resistant to most edged weapons.
The longsword (of around 4ft overall length and 1.5-2kg) is an excellent and powerful weapon against soft armour and unarmoured opponents, but lacks impact against heavily armoured opponents, where a mace or a polearm might offer advantages in bypassing (or straight out penetrating in the extreme case) the armour protection.
Armour and equipment weights add up though, and there is a limit to how much the character can usefully equip, especially before you can train your strength and stamina up.
In the Beta, the diplomat biased ‘mid game’ character wasn’t able to fully benefit from full harness, while the balanced and squire type character development examples had sufficient strength to operate normally when equipped.
There will be changes to some aspects of this before the final game releases, but the intent is sufficient realism to capture the essence of what is real without undue complexity. Clegane (and much of the GoT combat) isn’t anything like realistic.
