One Shanir ability appears to be a Voice of Command that compels another. This is displayed notably in To Ride a Rathorn, where Corrudin and Gorbel duel with conflicting commands on the Caineron Highborn cadet Kibben ; Gorbel's will is stronger and he is able to force Kibben to stand on his head. (This tug-of-war breaks Kibben; he eventually dies due to the fact that he is incapable of not following the order, regardless of who tells him to stop.) Corrudin then tries to make Jame order Brier to kiss her boots, and Jame withstands his will; she then tells him to "Back. Off.", to which order he finds his body responding without conscious thought. He retreats backward out of a third-story window, demonstrating the power of Jame's will even against other Highborn.
Earlier demonstrations of this power are given in Seeker's Mask. In Chapter 33, Caldane encounters Brier Iron-thorn as her ten-command, and Jame, retrace their steps after retrieving Graykin from his torment. Jame hears his voice and senses just how powerful Caldane really is. He turns a different side, though, when Jame leaps down and terrifies him. He floats in the air (this caused by the powder Jame put in his wine near the end of Dark of the Moon) and Jame pushes him out over the balcony until he's floating in the air in the central space of the Crown, and then commands him to look down and remember the sight, and her. Her command is strong enough to over-ride Caldane's will. Also, during the rope test of Tentir, when the Randir Tempter grabs Jame, Jame orders her, "Never. Touch. Me. Again." This order overrides even the commands of the Witch of Wilden, who is incapable of touching Jame while hag-riding the Tempter.
Torisen also displays the degree of his command when he forces Adiraina to answer his questions about Jame's whereabouts in the Women's Halls. However, when the Wolver Grimly comments on it later, calling it a 'nice trick,' Torisen nearly snaps his neck for suggesting that anything unusual happened (Torisen is incapable of dealing with the thought that he possesses a Shanir gift.)
Kirien possess this ability in some form, capable of forcing the truth from Index in Seeker's Mask despite the scrollsman's efforts to avoid it.