I haven't personally experienced the new system, but I gather it goes like this:

Every mage gets a "set" of amber (aura), sienna (shield) and black (barrier) rods. This set never changes for that particular mage. If another mage, who doesn't have one of those locations, looks in, he won't see anything. The guy who does have that location will see a wand. I think they actually appear when you walk into the room. So, if you walk through but don't get it out, then someone else could. Also, I gather that you only start seeing them once you're high enough level to actually use them.

There are also other a/b/s wands that aren't specific to any one mage. These are limited, and often at their limit. Typically these are named something *other* than "amber", "sienna" and "black", but I think there are some amber/sienna/black rods that aren't actually part of the "mage-assigned" group.

One thing I'm unclear on is whether particular a/s/b "groupings" are always handed out as a set, or if you're just randomly assigned aura, shield and barrier locations independent of one another.