What syntax "phrase" can I use to determine what actor has equipped a certain item.

What I wrote was:

"actor.getequipped.AAASecondpiece"

AAASecondpiece being the item equipped.

How do I say this correctly? Or is it even possible?

You might find the WIKI useful.

http://cs.elderscrolls.com/constwiki/index.php/CS_Functions

if actorREF.GetEquipped AAASecondPiece   ;do something here if its equippedendif

The thing is, I've read through most of the wiki prior to posting this question. But how it seems to me is that it is impossible to ask the computer WHO is wearing the item or WHO is attacking the person wearing it. The script works simply by asking if a particular person is attacking another particular person or if a particular person is wearing a particular item. I can't ask it a general question like "who is wearing the ring?" or "who is attacking the player?" through scripting.

If the script was an Object Script and running on the ring, you could use http://cs.elderscrolls.com/constwiki/index.php/GetContainer to determine who's carrying the ring.
Using it on a reference from outside the ring might not work, as it's quite impossible to obtain a reference to an object "inside an inventory" the way the game engine is handling these things.
Also it won't make much sense to ask this based on the ObjectID of the ring, as said ring can exist as dozens of instances of this Base Object.

Figuring out who's attacking the player is another question. Without the game or the CS I'm unable to figure it out right now, but it should be implementable as well quite sure. You might have to take care of choosing 1 from "multiple" enemies who are all attacking the player at the same time though.

With OBSE, another option is to walk through all the nearby actor references (getfirstref, getnextref) and check if they have the ring with getequipped. You can also check who they're attacking with getcombattarget.