Leveling DPS/Healing spec
Some of the best support you could offer is with the hammer. The auto attack puts down a symbol of protection (33% less damage).
She’ll probably be able to handle healing herself for the most part, but you can support her through boons. Shouts offer things like stability, protection and regen to allies. Five trait points into virtues can get you Inspired Virtues which improves your virtues. Virtue of Justice for might, Virtue of Resolve for regen and Virtue of Courage for protection.
A good guardian will cleanse his party member’s conditions too. Utilities like Purging Flames and Save Yourselves! work well, and the trait (IX in virtues) Absolute Resolution will add condition removal to Virtue of Resolve.
You’ll want gear with power on it while leveling. When you get up to two stats you can add precision or vitality depending if you want more dps or more survivability. Healing power won’t make your heals much better.