Yeah...the fledgelings were very tough. Which is totally opposite of my past encounters with them.
Also, NPCs don't necessarily follow the same atmospheres of players when it comes to combat. In many games you'll see them using a powerful weapon that you can't normally get--but they do drop a weaker version of it.
For the sake of balance and common sense, those are their weapons and theirs alone.
They could easily have vamp regen and +1 on them, along with vulnerabilities and on-hit effects meant only for an NPC.
As far as any character should be concerned, that vampire is holding a crummy sword it looted or just happened to find and will use it to try to kill you.
In short: These effects shouldn't exist in your character's knowledge anyway. If it's mean and it's swinging at you...kill it or run!
Not much RP in disarming no-drop weapons, other than it can be explained by you making a stunning blow on their arm or hand and they have to take a moment to recover. Of course it vanishes from sight, but keep in mind this is an old game so you have to use what's at hand.
Same explanation with knockdown. Both attacks are powerful swings (hence the penalty) and you can only expect to do either so many times before taking a hit on your own stamina or losing balance. You can disarm hundreds of NPCs in fights, but the one point still stands: You're killing it in regular combat (or it you), thus the RP is short-lived.
RP-fights of course are a different story but they follow the same principles.
Remember, you're just using a tough hit in a standard NPC fight. Unless it's possessed by a DM, don't expect too much from it. Usually controlled NPCs do RP fights anyway unless someone's really screwed.
