I've been to Belagarth once. Shield bashing was allowed, as was kicking other people's shields. It's dangerous, but nowhere near as dangerous as sharpened steel that has the advantage of a leveraged attack. If you sharpen the edge, you risk cutting yourself more than the enemy. Also, the reach is maybe a couple inches beyond your arm, rather than the 2 feet of a weapon.
Shields are really only good for stopping missile weapons. If arrows didn't exist, everyone would have had two weapons instead. A shield bash is good in a pinch, but as a go-to tactic, it's simply not as effective for disabling an opponent.
1. It is same as with reversed grip daggers- without any training or experience, there is actually high risk of self-inflicted damage.
2. BS, shield is good at stopping anything that did not penetrate it
3. Of course sword/shield combination is far more versatile than sword/sword or shield/shield, because either way you have
weapon in each hand (and it is better to have offensive and defensive weapon, than just weapon of one type)
4. Got any actual real life experience with shields to judge them so harshly?