You are limited to the abilities you are given, but you can make seven upgrades. Focus on upgrading Righteous Strike to level 3 first due to the fact it will be getting used around every 2-3 seconds so the increased damage reduction, damage, healing and resilience gain is perfect.
Followed by level 3 Radiant Pulse to protect your group and do additional healing and damage.
You can choose to upgrade Judgement instead of Pulse if your group members don’t stand behind your Radiant Pulse shield, but just remember you can cast Pulse twice for every one Judgement.
Put the remaining point into Divine Aegis, the character ultimate. If you use level 3 Pulse then this leftover point could go into Judgement to make enemies receive additional break damage.
Don’t forget that Judgement is a Taunt ability, so it will draw aggro from nearby enemies.