yes, you can roll trap claws using chips. just gotta be lucky to get a good cruel % combined with +trap skills. pray for 2 sockets instead of just 1.
cruel balrog blade? any magic weapon can be rolled cruel, if your rolling character is high enough to receive such a high mod.
character level does limit the potential magic level attribute being given to the item being rolled. cruel prefix is a lvl 51 attribute, so your character would have to be at least that level to possibly roll it onto the item.