Ooookay. I did another scientific experiment.

I dropped my main Dahlgren (skills in his twenties and thirties) in my handy-dandy arena I've built for such purposes with the following equipment.

Lvl 3 troll armor, lvl 3 bronze armor, lvl 3 bronze axe, lvl 3 bronze buckler, lvl 2 bone shield.

Food was deer stew, minced meat, queen's jam.

Spawned a troll three times one after the other and fought him.

1. Full bronze armor, bronze buckler, logger troll.
I was very surprised that I not only could block the troll but even parry it sometimes. Damage got through, but was mitigated by selfheal.

2. Troll armor, bone shield, logger troll.
As assumed, worked like above, but of course only blockable. Some damage got through, but was mitigated by selfheal.

3. Troll armor, bronze buckler, normal troll.
This was the real surprise! I could actually go mano-a-mano with a regular troll! Yes, damage was more, selfheal couldn't completely compensate, but it worked! Well, sorta.
I misstimed some blocks and I got crunched to 4 health.

At that time I cut my losses and flew the scene, with the tail tugged in. ;)

In the end, I was very surprised that the buckler actually could work in a troll situation as a last ditch measure.

Edit: I'm going to try this again, but this time with an abomination. Maybe a two star draugr as well.