First of all, i have to explain a few things :
ffa = free for all, which means public games. ( in which chaos reigns )
I will give 2 setups, with their pros and cons, but for the dueling tactics, this is something you have to learn by practising
#1 : The cheap bvbRings + amu = Angelic ( provides 10 dex, some rep life, d2m, life and ofc a huge amount of ar very useful )
helm : eth arreat zod / normal arreat sock ed/str or ed/dex ( i will explain later why )
Gloves : drakuls ( 15 str, 25 ow, nothing more to say )
they may be considered as lame (25 ow ), but draks are a very cheap and effective solution for a low budget bvb ( you can take steelrends as well, low stats ones are cheap, and steels provides far more def and dmg )
Belt : Verdungo : 15 dr, 40 vita, nice rep life and nice def.
Boots : upg gores ( best boots for bvb , and NO alternative )
Armor : forti ( mass dmg, some life, very nice def )/ eni (+2 all, mass frw, mass life, nice def, dr) ( eni can be used as well and is a very good option if you want to build a low str barb, but forti + grief is still the easiest way to play )
About forti, just take the one with the highest possible def and with a str req inferior to the total str you will have ( usually, people take ap, but you can use boneweave or balrog )
Weapon : Grief ba, highest dmg as possible, and minimum 34 ias.
Shield : storm , socked ed/dex or nice jwl ed/-req/adds
wc weapons : cta + hoto/3 wc weapon ( provides +7 bo and +4 shout ) or 2 x hoto / 3 wc weapons ( 6 bo 6 shout )
note that 1 bo ~70 to 80 life and 1 shout ( or 1 in iron skin ) is 2xx to 3xx def more
Inv : gc's 10/xx/3x or 3/15+/15+ sc's.
If you want to add some psn, just take 1 x 20 life 175 psn sc, it is more useful than a 451, since the difference after psn res reduction will be quite low, and you'll win a nice amount of life
Torch 20 stats, anni 20 stats, res don't matter a lot anyway since you only duel barbs.
Now, the part about statting and the pros and cons of that cheap barb :
Str is kind of easy to stat :
30 base
+40 torch / anni = 70
if you use draks 15 str then = 85
add 33 str to wear normal arreat ( 118 str req ) or 23 if eth zod arre
now, if you use storm with -req, 2 options :
1) you use normal arreat : you don't need to add any more str, you will have 138 str, and storm will be 133 str req. ( and in that case sock arreat with ed/dex jwl )
2) you use eth arreat : add 5 more str to reach 133 to wear storm.
If you use storm sock ed/dex : then you can either sock arreat with 40/9 str , therefore you will have 118 + 29 = 147 str, which means only 9 str to add, or if eth arreat, add 28 str
With that build, you should add between 42 ( if storm -req and arreat ed/str ) and 61 str ( eth arreat and normal storm ed/dex )
The choice between def, dmg, ar and life is about you.
There is no "optimal" build, this is just an example.
For dex, just add what you need to reach max block
All the rest goes in vita
#2 : The wealthy BvBRings + amu = angelics ( same reason than before )
You can also use 1 raven to save some dex, and it gives a nice boost to mana and dmges. ( even if the cbf is not rly useful in ffa bvb )
Armor : forti ( same reasons, mass dmg, some life, mass def ) ( go for ap / boneweave / balrog )
Gloves : steelrends ( this is a personnal choice ) = mass dmg, nice def , 10% cb
Boots : upg gores ( obvious choice , and again there is NO good alternative )
Belt : bug belt ( this is euro build )
Weapon : Grief Cb ( be sure to have 39+ ias on it ) + Bug fury ( this is euro build )
I chose sword, simply because it allows to use bug fury to lame, which can be very handful sometimes ^^
Shield : storm sock 30 max ( boosts grief dmg a lot ) or sock ed/dex or ed/ar/dex
wc weapons : wc weapons : cta + hoto/3 wc weapon ( provides +7 bo and +4 shout ) or 2 x hoto / 3 wc weapons ( 6 bo 6 shout )
And now, the tricky part , the helms :
There are ( imo ) 2 choices :
1) Rare barb helm 2 barb 2-3 bo/ base life / ar per lvl / nice def / 1- 2 socks / +1-3 in shout or iron skin socked with ed/ar/str/dex jwl ( even 2 if 2 os ^^ )
2) rare circ with 2 barb / ar per lvl / 40+ stats in str + dex / 1-2 socks
Note that on a barb, +1 in vita brings you ~10 life after bo, and +1 bo ~80 life.
so basically, if the circ has 24 stats ( base ) and 1 sock, and the rare barb helm 1 sock and 2 barb 3 bo, there will be no life difference in the end ( or maybe very little one ), the only difference will be the defense, which will ofc be higher on the barb helm. ( 100 more base def = 700 to 800 more def in the end )
But if the circ has fat stats, always prefer it over the rare helm, defense is a nice thing on a bvb , but imo not your 1st prio.
( to know which one is the best, either try them before with hero editor, or just make the calculations if you like mathematics, and just ask me if you didn't understant how to calculate )
Inv = full 32020's + 1 x sc life/psn or 1 sc life/cold ( using it to see when you hit )
torch + anni 20 stats, and get perf if you like ^^
Statting that build will mainly depends on your helm and if you decide to use draks or steelrends, so i won't bother explaining, if you are rich enough to afford this build, you should know how to stat it ^^
Skills :
20 ww
20 bo
20 shout
1 battle command ( even if you use cta, this is not a loss to put 1 point in it )
20 weapon mastery of your choice
1 natural res ( useful anyway vs ppl using psn )
1 increase speed 
NOT a must, some ppl like to play with frw ( like me ), some prefer not to. ( if you don't put 1 point here, you save 2 points that you should reinvest into iron skin)
Rest goes into iron skin
Pros and cons :
#1 cheap build
cheap (thanks master of the obvious) , works quite well if you just want a fun barb, but is quite hard to play since it's not the best statwise and itemwise
#2 rich build
costs a lot (again thx master of the obvious) , around 20k at least if you want something really good, but it's a pleasure to play since it has nice life, nice ar, nice dmges and all that combined with a gm build ( at least when you play with grief ^^ ) since it has only 10% ow ( becomes quite bm if you use bf )
The build is finished either @ lvl 99 if you put 1 in increase speed, or @ lvl 97 if you don't.
I did not add any point in berzerk, since using that skill in bvb is like suiciding.
Some people will abuse psn, in that case just go in town, take a few antidotes, and the lamer will just be as inoffensive as a slug.
About precast : i do not use any, and i do not like to use. Anyway, you can win vs people using precast, this is just a matter of skill.
Last thing : Imo the prios for a BvB should go this way : 1) ar/dmg 2) life 3) def ( i consider ar and dmg both at the same lvl, you need to find a balance that fits your gameplay )
There are ofc tons of possibilities and i won't list them all ( would be longer to do than listing every senseless thing mr "ty perz" wrote during his whole time on jsp)
Remember, these are only 2 examples of builds, which are in my opinion the most effective ways to go, depending on how rich bastard you are, and on your gameplay ( offensive, defensive, lamer...)
Feel free to adjust them to your budget and to what you likeI hope it's clear enough and that you enjoyed reading
Questions and comments are welcome ofc 