What arena gear to farm, and for what purpose?

fred4

Blackrose Prison
Mender's Ward (resto staff) - Sometimes recommended for "tomb healing", e.g. in trials such as vSS, where the healer slots and uses Healing Ward.

Spectral Cloak (dual wield) - A good filler set when using Blade Cloak already and you have room for this set.

Virulent Shot (bow) - Quite the nasty DOT when used with Magnum Shot, e.g. the knockback morph, in PvP.

Dragonstar Arena
Caustic Arrow (bow) - A decent (back bar) option in both PvE and PvP.

Destructive Impact (destro staff) - Hard to justify nowadays, since the base skill is so nerfed and the duration is too short as a back bar set. Might still have niche uses.

Grand Rejuvenation (resto staff) - A decent option for healers, if you happen to have room for it.

Puncturing Remedy (1H+Shield) - A must have option for any tank using Pierce Armor, especially when also using Tremorscale. The default for many tank builds.

Stinging Slashes (dual wield) - Used to be an oppressive PvP option, but got nerfed. Probably still viable, especially in dueling.

Titanic Cleave - Underrated AOE damage set with insane scaling. Flies under the radar due to all niche use cases, but there are many. OP for tanky solo play, including arenas (comfortable if slow), world bosses, and up to vet hard mode non-DLC dungeons. Good for trash pulls in general, lightweight tanking / dungeon group carrying, and even PvP brawling and bombing. Combining this set with sustain, such as Vicious Ophidian, is key to get the most out of it in PvE. Half of it's power lies in the base skill, e.g. Brawler and it's shield, but this set complements that skill so very well. Best class: Stamsorc, due to damage passives and Crit Surge healing synergising so well. Runner up: Corrosive Armor DK in PvP.

Archer's Mind - Might be worth looking into for a ganking build.

Footman's Fortune - An ancient tanking set. Not generally recommended anymore, but some blocking factors are additive. I believe that includes this set, even if that would need review with ZOS' constant changes. At any rate, this means that, in an actual build, the 8% could be far stronger than the puny tooltip indicates. If you ever want to explore the limits of block mitigation, this set could be worth looking into. That said, you should probably start by playing sorc and using the Bound Aegis skill.

Maelstrom Arena
Crushing Wall (destro staff) - An infused Maelstrom Inferno staff with a weapon/spell damage enchant is the #1 meta PvE DD back bar weapon for all classes. Enough said.

Precise Regeneration (resto staff) - It used to be quite meta. Probably still decent if your healer has nothing else to slot.

Thunderous Volley (bow) - If you want to back bar a bow, thereby using stamina, I believe this option performs close to the Maelstrom destro staff.

Merciless Charge (2H) - As with all DD back bar weapons you want it with an infused weapon/spell damage enchant and ground AOE skill, e.g. the Stampede morph. An alternative to Crushing Wall that might be meta for jabbing templars. However using this skill into a bar swap is finnicky. If you like ease of use, avoid this or arrange your rotation so you don't bar swap immediately after Stampede.

Winterborn - For a while this seemed to be meta for ranged magicka PvP gank combos of all things.

Vateshran Hollows
Executioner's Blade (dual wield) - I've executed fleeing targets in PvP with this, but it suffers from an unpopular base skill that, if anything, ZOS have ever more ruined over the years.

Frenzied Momentum (2H) - Was PvP meta for a while. Should still be decent to generate burst, and carries over through bar swap.

Point Blank Snipe (bow) - I don't play it, but I've run into dangerous melee Snipe players occasionally. I guess this must be working (PvP).

Void Bash (1H+Shield) - If you're not tanking with Master's 1H+Sield, you're probably using this. Nowadays you can also scribe an AOE pull skill though.

Wrath of Elements (destro staff) - A popular and effective PvP option for a popular and effective base skill.