Doing a little research, I've found wide discrepancies between weapon weights in the game and IRL. Here are some real life (mostly from wikipedia) weapon weights with a sample Oblivion weapon weight (all weights are in pounds):

battle axe: 1 - 6 / Elven battle axe: 55
*Claymore: 4.9 - 6.2 / Elven Claymore: 44
long sword: 2.4 - 3.3 / silver long sword: 28
**mace: 2 - 4 / glass mace: 35
war hammer: 2 - 8 / glass warhammer: 75

I'm wondering why the devs made them so heavy? If the purpose was to weigh one's character down so he/she couldn't carry an arsenal why not make the in-game carrying ceilings lower?

I understand it's a game, but why not make the weapons weights more realistic?

*A Claymore is basically a two-handed sword.
**I did find a mace that weighed 8 lbs.