"X damage done to attackers when hit by melee attacks" <-- this

Get from gear. Can stack up to 19.5K. If you can manage stack 5-6K consider quite OK.

When you use the Fierce Loyalty passive, if you pets get hit by melee (close attacks), they will auto deal the X thorn damage to the attacker. Without the passive, only you yourself will benefit.

If you are using that passive, try stack some Life Regen / Sec also since the pets will benefit from the auto life regen. 500 - 1K will be good for start. Max is about 4.1K.