leveling build?
You can pretty much use Greatsword with Scepter/Focus for leveling, since Greatsword is pretty good in AoE damage and Scepter/Focus gives you the range you need with Scepter and the defense you may need with blinds and blocks with Focus.
I suggest using the equipment that favours Power/Precision/Ferocity(mighty/honed/strong/berserker..) so you can damage foes quickly to move on in content.
Your traits could follow the building of one of the Guardian dungeon meta builds:
http://metabattle.com/wiki/Build:Guardian_-_GS_Sword/Focus
Or the Lootstick one under General builds for farming (the staff’s auto-attack tags 5 mobs in events so you can get greater presence in events):
http://metabattle.com/wiki/Build:Guardian_-_Staff_Farmer
Start the trait building from Zeal II (Fiery Wrath, every 10% bonus is great) or Virtues I (Unscathed Contender for 20% if you can keep up Aegis reasonably), then build up the staple 5 in Radiance with Blind Exposure, so you can get used to the Virtue of Justice spamming, since it is renewed every kill (with 3 in Radiance) and blinds enemies (1 in radiance) while giving might (with 1 in Virtues), so you can pretty much spam F1 every fight while using the blinds from Focus 4 or Greatsword 3 to blind enemies, while also making them vulnerable with the Blind Exposure trait (Radiance VI) giving them vulnerability, also upping your damage.
Good luck, and if you need a help with speed (since the Guardian is pretty slow), you can use the Staff 3 (Symbol of Swiftness) paired with Retreat! and/or Save Yourselves! for Swiftness.
Have a great time in Tyria!
Guardian main since launch
Also, in levelling try use some sigils of bloodlust/ speed on your greatsword. Having 25 stacks of power (base damage increase) will see you destroying most mobs with ease as well as having some free movement speed buff for a long duration. It’ll help with moving around the map. This is better for the Greatsword+Sword focus set up.
Although people may usually say this, a torch is highly viable in PVE, especially with those power stacks. All the more faster mob clearing