I run my Templar as a DPS Machine, in Light Armor so not a lot of tanking, but I can do that if needed for a while. In fact, I have to say that my Templar is the one character that I have rolled that I have to do something stupid to get killed. To many ways to heal your self in fights, like Puncturing Sweep if not skills from the Restoring line of their class.

If I was to do more tanking, I would sport at least two pieces of Heavy Armor (right now its 5/1/1 L/M/H). Tanking is something you do more in World Boss fights than anywhere else. Most PvE fights outside of World Bosses are DPS matches, tanking is not needed. Of course Group Dungeons are different in this regard. Public Dungeon Bosses, I tend to approach as a DPS focus more than a tank.

However I do heal with my Templar, just not with a Resto Staff, I use the skills from the Class Line. Repentance and Breath of Life and keep my allies alive that way. I just have one of them on my bar, Repentance for areas that have a lot of trash mobs, and BoL for other places.

Another thing to note, currently a Templar is a Magic character, it is 1.6 that allows you to Morph skills to scale from Stamina. So, right now, be a magic focused character. Also, while leveling, use a mix of armor types (L/M/H) so that you can build up those skills so end game you can use whatever armor you want. I run the Training trait on my M and H piece with Infused and Divines on the Light pieces. I use Light for the Magic bonuses. If I go Stamina, then I will switch to Medium for those bonuses.