Prince Xizor is an interesting pilot. His Highness' ability is outstanding at face value, but any further examination reveals a serious flaw.
His Grace can shunt hits that are not cancelled to his faithful companions. Combined with a bulky, inexpensive, and loyal companion such as the Syndicate Thug, this is a potent combo. You use His Excellency's three defense dice to cancel results, and hits that are not cancelled are absorbed by his true and loyal companion, the Syndicate Thug.
However, this assumes that the enemy will have the gall to target His Royalness, instead of focusing their attacks on his companion. Instead of His Grace's three defense dice, the Syndicate Thug is now protected by one defense dice, and will surely be destroyed.
How can the Noble and Just Prince Xizor make use of his ability, if the enemy is given an obvious route to counteract it?
The answer is that His Worshipfulness must exploit the enemy's reluctance to target him directly and punish them for it. His Highness' ability alters the natural target priorities of the enemy, and this is the effect that we must exploit to truly unlock His Highness' power.
We must turn His Grace into a monster.
By over-powering his Highness through upgrades, we can punish the enemy for attacking the Prince's companions instead of him. The key is to turn Prince Xizor into a threat that should not be ignored - because the enemy cannot efficiently focus him down.
His Highness could be made into an early or late-game threat. Here are two examples:
Early Game Threat:
Here, His Worship is outfitted as a super-maneuverable late game killer. The effectiveness of a very similar setup, for IG-88D has been explored by SableGriffon.
Here, His Grace is supported by his faithful Syndicate Thug companion, and the deadly Boba Fett.
In both cases, the lists exploit the inability of the enemy to effectively directly address His Highness Prince Xizor. They must either waste their fire directly attacking Prince Xizor, or waste it attacking his companion directly. In either case, His Highness is afforded protection. By avoiding enemy fire, His Grace can either deliver a punishing blow early on, or survive to the late game where His domination will be complete.