The flying saber had Aria momentarily distracted and she scarcely had the time to react quickly enough to flick her own blade up to block the blow. She dug in her heels in an attempt to resist the impact but it was to no avail and despite her best efforts her rearmost foot slipped, sending her stumbling backwards a few steps until she regained her balance once again and launched straight into another attack. 

She tried to be mindful of her Master's teachings. [i]Most Jedi will choose to face you with the Makashi form, keep on the offensive and keep pushing them. Makashi duelists hate to lock blades, you must force them to and you will always have the advantage.[/i]
"What do you think I mean, little Jedi?" she sneered as she tried to track his movements in the dim light. "You don't honestly believe your pathetic sister was here because she wanted to [i]help[/i] your Council, do you? In fact, as I understand it there was much she was all too willing to divulge to us. Much that gives [i]us[/i] the advantage in this war! You think we have been hiding from you? HA! You know nothing!"

In her haste to best him, she let her guard down and allowed his comment to get to her, after fighting for so long and so hard to prove herself it was too much for her to take and she had to retaliate.
"I'm not afraid! Fear is for the weak!" but beneath the anger there was mingled guilt and regret for something she had done, though what Yerbol would not be able to tell. But by having those emotions within her, no matter how deeply she had buried them in her attempts to ignore or conceal them from her Sith superiors, perhaps she was not so far gone that she was beyond redemption; however it would take more than a mere invitation of mercy to sway her.

Using the Force to propel herself onward she leapt sideways, producing a second lightsaber that had been hidden beneath her sleeve mid-leap, both blades spun at a speed that made it impossible to tell when one ended and the other began, arcing straight towards Yerbol's neck as she came back down in front of him again, using one of the columns as cover against his counterattack.
"Save your pity and your mercy," she snarled at him as she tried to push him back towards the grave again, "I have no use for it!"