(1) Learn to use goto commands to help control knockback. The bots are an extension of you, and like any user with knockback, positioning is key.
(2) Defense on your personal self isn't of a prime concern. Softcapping pet defense can be highly helpful, but your own state of affairs isn't terribly relevant. The damage done to you just isn't that large when you divide it up with 6 pets. If your decision is between a defense shield or a kb resistant immob, and knockback is giving you that much of a problem......the answer is very simple: Take the immob.....most bots players do. 
Ah the patron question: Mu does look attractive and the benefits of -kb in the immobilization is substantial. BUT, the OP is a Trick Arrow mastermind, with only a single protector bot shield to weather the alpha strike in bodyguard mode. Every bit of defense in bodyguard is defense to all six minions. If he were a /dark, /pain or /thermal mastermind, I would go for mu, you have the heal/auras. As a Trick Arrow, I highly suggest the Scorpion set. Your safety as you hit the debuff arrows will improve dramatically.
Triumphant Defenders Forever
Psylenz FF/Psi, ArticQuark Storm/Rad, Symon BarSisyphus Bots/psn, Max VanSydow Thugs/Dk, Cyclone Symon Bots/stm, Blue Loki Ice/Cd, Widow 46526
HelinCarnate:OMG it is so terrible. I have the option to take 3 more powers but no additional slots. Boo F'ing hoo.
Hello all, i simply have one question..
i am a robots/trick arrow mastermind and im noticing that my kb is very common, and i want to be able to keep mobs in the fire of my rockets and oil slick arrow,
the +defense shield from mace mastery would be much better for me defensively than the charged armor from mu, but the immobilize doesnt resist kb in mace :/
and so would it be better for me to go mace or mu for my bots/ta?
Jordon Justice