Sephiroth was weakened by Zack when cloud lifted him up and threw him in the mako. Turks are well taken care of and probably the best fighters cause they are hired by the president. Most people in the movies are poor. Since they are poor they can't take much. You can see the really powerful ones are healthy looking. Rude is meant to be a grunt so a big sign falling on him isn't suppose to be much. As Reno is smaller he couldn't handle a hit by Loz and sent him and Rude flying.