Permanent Retaliation Guardian
You're going to get hit. No matter how evasive you are or how often you pop Aegis, eventually you'll run out of resources and get beat down. Here, I'll try to make this work in your favor.
Apparently Retaliation got a tasty buff recently that improved its scaling. It seems fairly easy for a guardian to maintain it at all times, making quick work of glass-cannon gankers. The amount of damage Retaliation deals scales with Power, so we'll prioritize boosting that. Might also improves Power, thereby also contributing to Retaliation's damage. If we rely on people constantly smacking us, survivability is important, hence Vitality and Toughness (covered by a Soldier's Amulet). Critical Hits and Conditions are not a priority.
Something else that grants Retaliation: Light combo fields with Leap or Blast finishers. For this reason, the Greatsword and Hammer are clear choices for weapons, since each contains both components of that combo; other players and weapon swapping are unnecessary. Signet of Resolve is probably the best healing skill for a guardian, and it's the best choice here for reasons that will soon be apparent. Signet of Judgment is essential; it's a fast-recharging signet that provides Retaliation for 50% of its recharge time. This can easily be boosted to 100% with traits. "Stand Your Ground!" and "Save Yourselves!" also provide retaliation, but take much longer to recharge. Let's take them too, since more stacks wouldn't hurt and they're great skills in their own right (Stability is very useful, and covering Retaliation with every boon in existence is great). Tome of Courage will help keep you alive when you're under too much pressure, but Tome of Wrath might also be fine.
Trait selection is a little difficult. We have a lot of elements we'd like to bring together, and the traits that would benefit us are numerous and spread across every trait line. We like Power, and both of our weapons have a Symbol (i.e. Light field), so Zeal is an important trait line. We don't really care about Condition Duration, but that helps us maintain the Weakness that our Signet of Judgment will be constantly spreading. We also have a lot of Greatsword-related traits here, so investment is valuable throughout. The Minor traits each boost Symbols, and Greatsword Power and Zealous Blade are the obvious choices for Master and Grandmaster tier. Since both of our weapons can Immobilize, Binding Jeopardy makes the only reasonably effective Adept-tier trait.
Signet Mastery is essential. Not only does this reduce Signet of Judgment's recharge to a manageable 16 seconds, it synergizes with our heal skill as well. Radiance is best reserved for crit/condition builds, so investment past this point is unwise (although Healer's Retribution is tempting). While Toughness is an important stat, the traits in Valor are not helpful and our attention is best directed elsewhere.
Just as we need quick signets, Shout Mastery is important to speed up our other two utility skills. The most important trait we need is Vengeful, which brings the Retaliation provided by our utilities to 15 seconds instead of 10. The ten points we put into Virtues in order to access this trait brought our Boon Duration bonus up to 10%, and that extra second is all we need to raise Signet of Judgment's Retaliation duration to 16 sec - exactly as long as the recharge. Our last 10 points could be placed in Virtues to get the Virtue of Retribution Minor trait, but the most effective choice is Two-Handed Mastery in Honor, which reduces the recharge on all of our weapon skills.
Remember, Might boosts Power, which boosts Retaliation, so let's get equipment that gives it to us. We're only getting critical hits less than 10% of the time, so we're better off with Sigils of Battle rather than Strength. Runes of Strength synergize most effectively with Might application, so get those. Runes of Sanctuary apply Retaliation, but we can't apply Frozen, and Power is more important. A Soldier's Amulet and Jewel conveniently boost all the stats we care about while prioritizing Power. We're left with crazy high Power and enough health and armor to be viable.
Skills
Weapon: Greatsword of Superior Battle; Hammer of Superior Battle
Aquatic Weapon: Spear of Superior Battle; Trident of Superior Battle
Healing Skill: Signet of Resolve
Utility Skills: Signet of Wrath, "Stand Your Ground!", "Save Yourselves!"
Elite Skill: Tome of Courage
Traits
Zeal 30: Binding Jeopardy, Greatsword Power, Zealous Blade
Radiance 10: Signet Mastery
Honor 20: Shout Mastery, Two-Handed Mastery
Virtues 10: Vengeful
Equipment
Armor: Superior Runes of Strength
Amulet: Soldier
Jewel: Soldier
Calculator Link
You're going to get hit. No matter how evasive you are or how often you pop Aegis, eventually you'll run out of resources and get beat down. Here, I'll try to make this work in your favor.
Apparently Retaliation got a tasty buff recently that improved its scaling. It seems fairly easy for a guardian to maintain it at all times, making quick work of glass-cannon gankers. The amount of damage Retaliation deals scales with Power, so we'll prioritize boosting that. Might also improves Power, thereby also contributing to Retaliation's damage. If we rely on people constantly smacking us, survivability is important, hence Vitality and Toughness (covered by a Soldier's Amulet). Critical Hits and Conditions are not a priority.
Something else that grants Retaliation: Light combo fields with Leap or Blast finishers. For this reason, the Greatsword and Hammer are clear choices for weapons, since each contains both components of that combo; other players and weapon swapping are unnecessary. Signet of Resolve is probably the best healing skill for a guardian, and it's the best choice here for reasons that will soon be apparent. Signet of Judgment is essential; it's a fast-recharging signet that provides Retaliation for 50% of its recharge time. This can easily be boosted to 100% with traits. "Stand Your Ground!" and "Save Yourselves!" also provide retaliation, but take much longer to recharge. Let's take them too, since more stacks wouldn't hurt and they're great skills in their own right (Stability is very useful, and covering Retaliation with every boon in existence is great). Tome of Courage will help keep you alive when you're under too much pressure, but Tome of Wrath might also be fine.
Trait selection is a little difficult. We have a lot of elements we'd like to bring together, and the traits that would benefit us are numerous and spread across every trait line. We like Power, and both of our weapons have a Symbol (i.e. Light field), so Zeal is an important trait line. We don't really care about Condition Duration, but that helps us maintain the Weakness that our Signet of Judgment will be constantly spreading. We also have a lot of Greatsword-related traits here, so investment is valuable throughout. The Minor traits each boost Symbols, and Greatsword Power and Zealous Blade are the obvious choices for Master and Grandmaster tier. Since both of our weapons can Immobilize, Binding Jeopardy makes the only reasonably effective Adept-tier trait.
Signet Mastery is essential. Not only does this reduce Signet of Judgment's recharge to a manageable 16 seconds, it synergizes with our heal skill as well. Radiance is best reserved for crit/condition builds, so investment past this point is unwise (although Healer's Retribution is tempting). While Toughness is an important stat, the traits in Valor are not helpful and our attention is best directed elsewhere.
Just as we need quick signets, Shout Mastery is important to speed up our other two utility skills. The most important trait we need is Vengeful, which brings the Retaliation provided by our utilities to 15 seconds instead of 10. The ten points we put into Virtues in order to access this trait brought our Boon Duration bonus up to 10%, and that extra second is all we need to raise Signet of Judgment's Retaliation duration to 16 sec - exactly as long as the recharge. Our last 10 points could be placed in Virtues to get the Virtue of Retribution Minor trait, but the most effective choice is Two-Handed Mastery in Honor, which reduces the recharge on all of our weapon skills.
Remember, Might boosts Power, which boosts Retaliation, so let's get equipment that gives it to us. We're only getting critical hits less than 10% of the time, so we're better off with Sigils of Battle rather than Strength. Runes of Strength synergize most effectively with Might application, so get those. Runes of Sanctuary apply Retaliation, but we can't apply Frozen, and Power is more important. A Soldier's Amulet and Jewel conveniently boost all the stats we care about while prioritizing Power. We're left with crazy high Power and enough health and armor to be viable.
Skills
Weapon: Greatsword of Superior Battle; Hammer of Superior Battle
Aquatic Weapon: Spear of Superior Battle; Trident of Superior Battle
Healing Skill: Signet of Resolve
Utility Skills: Signet of Wrath, "Stand Your Ground!", "Save Yourselves!"
Elite Skill: Tome of Courage
Traits
Zeal 30: Binding Jeopardy, Greatsword Power, Zealous Blade
Radiance 10: Signet Mastery
Honor 20: Shout Mastery, Two-Handed Mastery
Virtues 10: Vengeful
Equipment
Armor: Superior Runes of Strength
Amulet: Soldier
Jewel: Soldier
Calculator Link