I thought that the paragon powers where good especially for encounter powers, each can hit multiple times which is where your sov comes in handy. This would be a good time for the bg of fury to use a power that marks those around him, and then uses slave to fury, so the enemy either attacks some one else and triggers divine sanction or attacks the bg and recieves the punishment of slave to fury.
Proof of Domination is cool too, especially if a power draws the enemies all around you so that you can nail them all. Hit say five and you 15 temps, deal 2w damage, and weaken the enemy plus deal your striker damage. Most encounter powers at 11th level deal 2w damage or maybe three or if a close burst 1 weapon attack deal 1w damage.
The sov could be good for multiple enemy attacks. All so it has no line of effect so you could teleport it behind a wall and use your minor action to ask it what it sees.
Also I am wondering if that is equilent to the first mount feature then what is the equilent to the next feature? The one where you grant flight to other characters and stuff. Greater Servant of Vice?