Yes, your typical Aspis (Aspis - Wikipedia) was about 16 lbs. or 7 kg., but depending on the size a range of 13-18 seems reasonable.It really depends on the type of shield - as @Neonchameleon pointed out, viking shield usage was different, and bucklers certainly were used differently too. However, the type of heavy shield protecting mostly the torso used in this film was fairly similar to the ones we used, and heavier too - 13 to 18 pounds if a quick googling is accurate.
IIRC because he was using not just the shield but his whole body (pretty much) to force Achilles's spear down? I doubt he was in position at that moment to counter-attack.But why wait until Achilles' spear is free?
Yes, Achilles is a demi-god for the most part. At the level he would represent, many players do see PCs in D&D as superheroes. Even the DMG calls them superheroes in tier 4, which I would certainly place Achilles in. Hector, however, would be solidly in Tier 3 IMO.See, I don't think it does because Achilles is not human, he's almost a demi god. I guess it depends if you think that D&D heroes should be heroes or superheroes?
I think the main objections raised are more to do with:Not only is spear and shield not cheesy, but fighters (at least) should get d4 bonus action attacks and "power attacks" with any melee weapon as a class feature. Fight me!
It's just bad fluff. The bonus action attack is fine, mechanically, and different fluff would even make sense.1 - Wielding a quarterstaff one-handed. (Not making a specific strike one-handed, but actually swinging it with control, opposing an opponent's weapon with it etc.)
2 - The butt-stroke with a spear in one hand. Yes, lets take that dedicated stabbing implement and try to rotate it along its long axis, away from threatening your opponent in attack position, with all the leverage that you can apply with a single hand.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.