Ill take a crack at it.
1st-The qualifications:
*For SA+Rudras (TA Rudra would be a little different)
*Uncapped Fstr (so prob not abyssea. Some things would change if you assume fstr cap)
Augments:
Heca cap with atk+10 and DA+(not sure what DA cap is. Ive seen 4)
Heca Sub: Augments irrelivant. Acc be the only one that would do anything. (Crit rate wont help rudra)
Heca Feet: Str5, atk6 (i think those are the caps for those augments)
Torn on Rajas vs thundersoul. The WS itself is almost exactly 1dex=2str. So -2dex on thundersoul>rajas needs 4str to compensate. Rajas has 5 AND that gives 2.5 atk so it wins hands down, but if you toss in SA, 1dex=4str for that, then theres the 20% bonus from AF3 hands+2. (TA Rudra or solo rudra rajas wins every time unless Fstr is capped)
So 2 dex adds:
SA=2.4 base damage (2-3)
Rudra=1base damage*FTP. Using 200ftp(Fussetto)4.25 or 300tp 5.25.
Offhand=1base damage.
So WS between 100tp(200fusetto) and 200TP(300 fusetto), 2dex gives min/max of:
100tp(200): 7.25-7.65 base damage
200tp(300): 8.25-8.65
So how much str does it take to beat that? Unfortuantely, Fstr only gets counted once when stacked (only in WS, not on SA when stacked) unlike dex. So it has a more uphill battle. 4str=1base*FTP and +1 for offhand hit.
4str adds:
100tp(200):5.25 base damage
200tp(300):6.25 base damage
So to cut this down to 1str/dex:
1dex:
100tp(200): 3.625-3.825 base damage
200tp(300): 4.125-4.325
1str:
100tp(200):1.3125 base damage
200tp(300):1.5625 base damage
At 100tp: 1dex=2.76-2.91str
At 200tp: 1dex=2.64-2.77str
Rajas/Thundersoul=5str vs 2dex so its a
1dex=2.5str
Caveats:
*Close calls go to str from the added atk.
*Individual results will vary based on rounding of 3 factors: Fstr rounding 5str=1.25 fstr 'usually'. rounds to 1 or 2. 2dex on SA. AF3+2 gives 20% dex bonus =2.4. Rounds to 2 or 3. WSC will take that 2 dex and make it 0 or 1.
*Each additional hit (DA or TA proc) faavors str more. without SA, 2dex=4str so 5str rajas gets more from more hits.
The setup i proposed is based on the avg, not the exact which is determined by mob vit, your exact str, and your exact dex.
So worst case scenario, your at 100(+100) TP and your 2dex rounds down on both SA and WSC for a whopping total of +2 base damage on SA, 0 on WS (VERY rare). Str is guranteed +1Fstr for a minimum of 4.25+1 damage. Max for dex is 3damage on SA, 4.25+1 on WS at 100+100tp for a total 8.25. Max str bonus would be 2fstr so 8.25(25% chance of this)
Anyway, long story short, Rajas is VERY close to thundersoul which would let the 2-3 atk from the 5str push it up to the level of "it dont make a lick of difference". If you would like to figure out your EXACT dex numbers for WSC and SA to see if that 2dex is getting favorable or unfavorable rounding, be my guest, but its not really worth it to me.
Also note that TA+Rudra removes the 2-3 bonus from the 2dex on SA and thus looses every time to 5str.
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TLDR:
Generalizations (assuming uncapped Fstr):
*Solo Rudra: Raja>Thundersoul
*TA+Rudra: Raja>Thundersoul
*SA+Rudra: VERY close. Rajas almost matches without AF3+2 SA Dex bonus. 2-3atk will make up the gap (result subject to rounding)
*SA+Rudra+AF3 hands: Thundersoul edges out rajas by a small margin *IF and ONLY IF your dex rounds favorably on BOTH SA bonus and WSC.
*Capped Fstr: Rajas looses.
I stick with rajas because it covers all my bases. If i wanted to be over the top, i could figure out if a 2nd thundersoul would be good or bad dex rounding for my specific gear, but inventory-1, -550k gil, and the extra macros of a separate WS gearset for SARudra, Solo Rudra and TA rudra=to much hassle to 'sometimes' see 10 more damage on SA+Rudras.