The total set adds Killer Effect +16, presumably +16%. Similar to the job ability Warding Circle, which purportedly gives +15% damage bonus, -15% DT, would this set not give +16% acc/atk/evasion for the majority of mobs?
No, it's just intimidation unless you equip something like the founder's piece which augments it to increase damage dealt and reduce damage taken.
Do the killer effects apply to every mob? How des that work.
Only mobs that have an applicable killer effect already, so no beastmen mobs like orcs and quadavs
Works in Omen on the bosses too. Empty Killer (exists but don't know if killer effects gear includes that) for mid-bosses and Arcana Killer for the main bosses. You do a buttload more damage and take less too. That's why DRK is nice as a DD in omen.
From BG wiki:
While the Job Trait variations vary in potency via level, the innate boost for monster affinity is:
5% intimidation rate to enemies of the prey species. Verification Needed
+5% damage dealt to enemies of the prey species. Verification Needed
-5% Special Damage Taken from enemies of the prey species. Verification Needed
The damage reduction from Killer Effects is calculated as a multiplier after gear reduction totals.
The damage bonus from Killer Effects is calculated where the affinity term exists in a damage equation or as a direct multiplier where they don't exist.
The bonus from Killer Effects cap at +50%. Verification Needed
The potency of Killer Effects gained by Job Traits is halved against Notorious Monsters, but Killer Effects gained from gear is unaffected.[1]
https://www.bg-wiki.com/ffxi/Category:Killer_Effects