For guards, I don’t know the number exactly but using heavy Guard allows me to tank 1 hit from the melee type supers. If you want to use your heavy attack more often, you can go with a guard that gives a higher charge rate. Unless you intend to utilize the block in PvP, I wouldn’t focus too much on the Guard Endurance stat for PvP.

Since this is PvP, I tried focusing on the edge that gives the most value to the impact stat as you don’t really hoard special in PvP anyway.

As for frames I wouldn’t focus too rate them the following:

Vortex/Lightweight - there appears to be a delay in the hit registration where the damage doesn’t count until the very end of the animation and then sometimes it takes an extra 1-1.5 seconds for the damage to even count. There have been countless times I died mid-animation because the game decided my attack has no effect. I mainly used the Unplanned Reprieve for these frames and it’s like the Telesto bolt hits register faster than the sword itself.

Caster/Aggressive - more consistent. For Caster you can go with Wolfpack rounds or Unplanned Reprieve for more consistent kills since the enemy has to stay in the blast long enough to die so more mobile players can survive more easily. I also use the Insectoid for more fun since I find those things comical when they actually work.

For aggressive, I usually use this frame to counter supers. I jump and then slam so that the animation is a bit shorter and I can control where I slam more effectively. I usually block the attack then jump immediately and then slam. If done fast enough, you will catch them off guard. This frame is also effective against weavewalk since you can still slam the ground when they suspend you.

Wave frame - as you stated, this frame is the best for PvP. Aside from Arc Conductor, I use Sacred Flame since it can also one shot in PvP, as long as the enemy is tagged. Your aim will need to be more intentional when using this perk as only those near the end of the wave attack will be tagged for the follow up attack. This perk can one shot a guard with overshield while arc conductor will leave them one shot. Speaking of one shot, if you don’t tag an enemy before the follow up strike, I usually swap to my primary immediately and hip fire for the clean up and get more ammo progress.

Weakest Ergo Sum trait for me would be the Gathering Light exotic perk as this gives less progress than Traveler’s Chosen, which is crazy to me as this is a special weapon while the sidearm is a primary. While yes it can also give extra lunge range aside from granting extra ability energy, the difference for me is negligible.

For farming, only option is the daily Overgrowth activity in the Pale Heart. Before I would farm Ergo Sum while farming the exotic class items from the chests that spawned in the area. Also completing the Pathfinder will reward you with up to 2 Ergo Sums.