Graendal is holding the TP and using a dove to spy on Rand. She sees him take out the Access Key and quickly figures out what he's planning. She releases the TP, and in a panic, almost fails to embrace Saidar.

She then first weaves a Gateway. After that, Aran'gar, who's watching out of the window, makes a comment about how much of the Power Rand was holding. Graendal realizes that since Aran'gar and Delana wove compulsion on Ramshalan, they'd have to die, or else Rand would think Graendal was alive. So she slams a shield into both of them, and ties them off. As she does this, both women gasp. Delana gasping is no surprise, since she can see Graendal weave a shield. Thus, she may not have been holding the source. That Aran'gar gasped implies to me that she was holding the source, and felt it get cut off (and it makes sense that she was holding the source. Rand had just channeled enormous amounts of the OP). After tying off the shields, Graendal now wraps the two women in Air, and flees through her Gateway. At no time is the angreal mentioned.

Some critical things:

Graendal is confident that Aran'gar cannot break through her shield anytime soon. Since she made it really really fast, I doubt she made a complicated knot. That means that Graendal is enough stronger than Aran'gar that the other woman can't easily brush off her shield.

Graendal is a really fast channeler. That even in a panicked state she could do so many things that required so much power implies to me that she is one of the most skilled among the Foresaken. I think only Lanfear could have done the same.

More than anything else, Graendal is an intelligent channeler, which makes her much more dangerous than her strength alone would have. She's certainly been set up as Moridin's counterpart among the females, with her TP access.

Nynaeve has insane skill with Healing. The way Graendal phrases it, someone with the ability to read her compulsions is extremely rare. It might interest you to know that before she figured out that Rand was going to BF Natrin's Barrow, Graendal made a plan to kill Nynaeve.