Which merc is best for pvp and what equip for:

Hammerdin - a1 merc with Ice?
PB necro - ?
Wind druid - ?

this is just me:
andys fort ecv insight, if i am dueling a ias melee char (bowzon or zealer for example) i can put on doom on merc
bone necro: it really depends on what i am dueling but andys fort ecv insight is most common most useful
windy druid ecv insight andys ebug fort sa with doom in stash nothing complicated

ww barb bvc mode i a bone vistage with 3x 40/15s + ebug ap fort and faith 2/15 in a diamond bow or hydra bow depending what i find, enchant your merc with 6.7k enchant and leap fhr lock to abuse players off screen

But mercs is not allowed in pvp

i am so glad you follow the rules

"How can I be as BM as possible during a duel"

Hammerr - if you want a1 do a fire Merc (more range). With windforce with Lo socceted. 20s helm with ar% mod and deadly strike with 15/40's and fort or a 40s armor with 4x 15/40. If you have aura swap this Merc will 1 shot people

Pnb necro - BOTD warpike with fort and same helm as above. Cast amp and Merc will 1 shot. 40# armor with 40/15s also good.

Wind druid - same helm as above, fort and reapers toll. Reapers will also make your druid do more damage only use reapers unless you're retarded.

Basically for PvP you want 1 shot damage which comes a lot from having big damgas with deadly strike. For hammering if you want a2 Merc use the same as pnb necro above and use might aura although blessed aim could also be helpful or holy freeze too. You could also use doom instead of botd, but botd warpike on an hammerman or necro with amp really hit hard.

You're welcome and too bad this game has ran it's course