My thoughts on scimitars:
You only give up 1 cut damage to get a very powerful stab (Elite Scimitar->Italian Sword), so most people would rather get the stab. Some people have problems blocking the curved model, so that's worth something too, but I don't think it makes a big difference nowadays (I spent some time on duel with a +3 Elite Scimitar a while ago, and people seemed to block it as often as the straight swords).
In my opinion, if you are going to give up stab, you should get more than 1 swing damage in return. 3d 1h weapons like the Military Cleaver, Broad 1h Axe, Spathovaklion, and Liuyedao get Massive Cut Damage, Shield Breaking, Knockdown, and Crazy Speed (respectively), which are worth giving up a stab for.