Sirina wasn't in a hurry to teach Sol new techniques, she simply waited till he perfected the ones he had. They had barely over three weeks before they needed to head out for their mission, so there was no time to waste.
As soon as Sol was done eating, they continued practicing Aura Guard. Under her supervision and help, Sol's proficiency began rising visibly.
From Sol's battle with the Ashen Claw Lynx, Sirina realized Sol wasn't lacking in skill, but techniques to help him adapt to situations. After pondering for a while, she decided it was time to start teaching him some veil-blade exclusive techniques.
The first technique was the Veil-Step. This allowed Veilblades to blend into shadows, temporarily phasing out of sight and sound. They learn to use ambient darkness or even cast their own shadows to disappear.