from what i have noticed, the rams are NOT aggressive as one would expect. They are actually dwarf species and are classified as "peaceful". There are times when my rams pick on the angels mainly during feeding but i have also seen them eat off the same cube before. I did have my 2 rams have their first spawn about 2 weeks ago and during that time they were very aggressive but only to fish that get close to their cave. Since the initial spawning (lost all eggs due to midnight raids-sterbai cory's) they are a bit more aggressive when other fish approach their cave, but generally let everything slide.
What other tank mates do you have? How many rams do you have? 2 males, 2 females, 1m/1f? the sexes (from what i have noticed) make a huge difference.
When i first got my rams, i had 4 males and 5 females and i lost aobut half due to fighting, but thats interspecies fighting and is expected among that type of fish.
i just read that you have a knife in your tank. how big is he/she? my assumption is the knife is your issue. If he is still small-that might explain the nicks and dings. when he gets bigger i am afraid you wont see any evidence of his bullying. the knife will eat everything he can fit into his mouth and if he cant fit it, he will still try until he finds out he cant fit them.
hope it helps
here is a quick video of my tank YouTube - MaxsPlantedTank