What do you mean by "ultimate swordsman?" Because it's very likely to be outperformed by any of a few much simpler builds, especially if you're specifying <= tactician difficulty.
On tactician, 5/5/2 warlock/pala/fighter will be a 3-hit/action class that can completely skip STR in favor of CHA, has action surge, has 2 fighting styles, has warlock's outstanding level 3 spells, and can use the warlock spell slots to also fuel smites on short rest.
A very simple 12 BM fighter gets 3 extra feats over your build and likewise has 3 attacks/action. Functionally, that same fighter will always get 4 attacks/turn without the war priest dip because they'll have GWM and it's not very likely they won't either kill or crit *something* on 3 attacks.
4/8 thief/oathbreaker can abuse arcane synergy, aura of hate, and the [[harmonic dueller]] to get great damage out of a dual wielding build.
11 ranger hunter gets whirlwind attack (and volley), which are arguably the only single martial feature(s) stronger than improved extra attack. The build can take 1-dips into cleric for a radiant orb/debuff control build or warlock for GOO fear on crits - and they'll get a lot of crits with all of the attacks/turn.
[Harmonic Dueller](https://bg3.wiki/wiki/Harmonic_Dueller) is a rare +1 Rapier that when activated, can grant all the wielder's melee attacks extra damage equal to their Charisma modifier.
^This ^action ^was ^performed ^by ^a ^bot. [^(Learn more)](https://www.reddit.com/user/BG3WikiFetcher/comments/1bk01df)
tbh this is just a worse 10/2 Bardadin. Same amount of attacks, less spell slots, less ASI's so you're only at 18 STR or DEX. You have a better turn 1 nova... maybe, if you hit. But then turn 2 the 10/2 Bardadin just keeps smiting away with more level 4 spell slots, plus Counterspell on reaction. And turn 3 same deal. Plus why would i go War Cleric for extra attacks when i can Duelist's Prerogative for the same thing and get another bard level or another fighter ASI? Or use Scoundrel and throw out a Bonus Action level 6 Hold Monster and now the bossfight is over? Yeah I see what you're going for but Opportunity Cost is real and it's a doozy.
The comments on this thread have tended heavily toward criticism, which I find a bit disappointing.
Yes, 10/2 is the honour mode meta build, and oathbreaker bladelock the non honour mode equivalent but let's not all jump on the optimisation/opportunity cost bandwagon on a game that's renown for not actually being all that hard.
I really like this build. It has lots of neat synergies that I'm a big fan of. Getting your full caster slots from swords bard to increase spellcaster level to get two max level smite slots and managing to squeeze in BM 3 for maneuvres. You can't use maneuvres and flourishes at the same time, but with 8 × 1d8 in total you can smash at least 4 out in the opening action surge nova round and have 4 left over to mop up anything left alive.
You have just the one feat; will you be taking Savage Attacker? My feeling is to go with 17 Dex and take hag hair and mirror to make it 20 end game; that should be plenty and you won't miss much with attack roll bonus gear and abilities.
Someone mentioned Duellists Prerogative; I think that's a great option and would make the War Cleric dip redundant. If you used this weapon it may be a good idea to dip into Wizard instead for the Shield spell and scribing up to Level 4 spells? Duellists also gives an additional reaction, so would work well with Shield and Riposte. You'd have a reaction for if an enemy in melee range either hits or misses
EDIT: Ran some numbers on a spreadsheet I'd been using to come up with Paladin builds. With Duellists Prerogative and typical late game damage riders, you're looking at 60-70 dmg on a typical smite. So 180-210 dmg on a typical round; 300-350 dmg on the action surge round. Plenty to obliterate anything on Tactician, or Honour for that matter
What do you mean by "ultimate swordsman?" Because it's very likely to be outperformed by any of a few much simpler builds, especially if you're specifying <= tactician difficulty. On tactician, 5/5/2 warlock/pala/fighter will be a 3-hit/action class that can completely skip STR in favor of CHA, has action surge, has 2 fighting styles, has warlock's outstanding level 3 spells, and can use the warlock spell slots to also fuel smites on short rest. A very simple 12 BM fighter gets 3 extra feats over your build and likewise has 3 attacks/action. Functionally, that same fighter will always get 4 attacks/turn without the war priest dip because they'll have GWM and it's not very likely they won't either kill or crit *something* on 3 attacks. 4/8 thief/oathbreaker can abuse arcane synergy, aura of hate, and the [[harmonic dueller]] to get great damage out of a dual wielding build. 11 ranger hunter gets whirlwind attack (and volley), which are arguably the only single martial feature(s) stronger than improved extra attack. The build can take 1-dips into cleric for a radiant orb/debuff control build or warlock for GOO fear on crits - and they'll get a lot of crits with all of the attacks/turn.
[Harmonic Dueller](https://bg3.wiki/wiki/Harmonic_Dueller) is a rare +1 Rapier that when activated, can grant all the wielder's melee attacks extra damage equal to their Charisma modifier. ^This ^action ^was ^performed ^by ^a ^bot. [^(Learn more)](https://www.reddit.com/user/BG3WikiFetcher/comments/1bk01df)
tbh this is just a worse 10/2 Bardadin. Same amount of attacks, less spell slots, less ASI's so you're only at 18 STR or DEX. You have a better turn 1 nova... maybe, if you hit. But then turn 2 the 10/2 Bardadin just keeps smiting away with more level 4 spell slots, plus Counterspell on reaction. And turn 3 same deal. Plus why would i go War Cleric for extra attacks when i can Duelist's Prerogative for the same thing and get another bard level or another fighter ASI? Or use Scoundrel and throw out a Bonus Action level 6 Hold Monster and now the bossfight is over? Yeah I see what you're going for but Opportunity Cost is real and it's a doozy.
What is the leveling order and when do you consider it to be fully “online”?
The comments on this thread have tended heavily toward criticism, which I find a bit disappointing. Yes, 10/2 is the honour mode meta build, and oathbreaker bladelock the non honour mode equivalent but let's not all jump on the optimisation/opportunity cost bandwagon on a game that's renown for not actually being all that hard. I really like this build. It has lots of neat synergies that I'm a big fan of. Getting your full caster slots from swords bard to increase spellcaster level to get two max level smite slots and managing to squeeze in BM 3 for maneuvres. You can't use maneuvres and flourishes at the same time, but with 8 × 1d8 in total you can smash at least 4 out in the opening action surge nova round and have 4 left over to mop up anything left alive. You have just the one feat; will you be taking Savage Attacker? My feeling is to go with 17 Dex and take hag hair and mirror to make it 20 end game; that should be plenty and you won't miss much with attack roll bonus gear and abilities. Someone mentioned Duellists Prerogative; I think that's a great option and would make the War Cleric dip redundant. If you used this weapon it may be a good idea to dip into Wizard instead for the Shield spell and scribing up to Level 4 spells? Duellists also gives an additional reaction, so would work well with Shield and Riposte. You'd have a reaction for if an enemy in melee range either hits or misses EDIT: Ran some numbers on a spreadsheet I'd been using to come up with Paladin builds. With Duellists Prerogative and typical late game damage riders, you're looking at 60-70 dmg on a typical smite. So 180-210 dmg on a typical round; 300-350 dmg on the action surge round. Plenty to obliterate anything on Tactician, or Honour for that matter