It's probably not the playstyle you want (still melee though), but respec into a rapier build, the rapier's super fast attacks make playing turn based Dark Souls much easier. It's your turn more often, and they do really good damage due to their insane counter attack scaling.
Core outline is pretty simple:
105 AGL, (up to) 40 DEX, Stamina soft-cap at 20 END
Old Leo Ring, Ring of Blades
Rapier, Espada Ropera or Ice Rapier (2-handing rapiers is generally the better option)
The regular Rapier has the lowest stamina cost while the Espada Ropera has better DEX scaling and the highest durability. The Ice Rapier is special insofar as infusing it does not tank the weapon's physical damage too much. I would also recommend running the Ring of Stone outside of boss fights because that gives the rapier enough poise damage to stun lock most enemies, including phantoms, which leaves you with one free ring slot to play with in levels (like the Ring of Binding) and up to two for boss fights - you can use the best defensive options and stat boosts as you want.
The reason why this works so well is the scaling from counter attacks, which is, during boss fights, pretty much all the time. Rapiers have a 140 counter damage rating, the Old Leo Ring boosts that to 157.5, meaning as long as you attack during an enemy's attack or recovery animation, you deal ~60% more damage per hit. The Ring of Blades adds flat extra damage per attack, which is ideal for a weapon with quick attacks and a large percentage boost on many of these attacks.
Ricard's Rapier is an option too, but its lower base damage is only offset by the better DEX scaling once you reach 40 DEX and beyond, and it's heavy attack is a flurry that shreds weapon durability - and the damage difference is not that consequential even after it catches up with its scaling. For how much people seem to love this weapon, it's a bit of a paper tiger. The effects of seeing big numbers on your screen, I suppose, a well placed flurry attack can deal tremendous damage to a boss. Looks fantastic, but a regular rapier isn't far behind in the same time span and doesn't break from usage as quickly.
From there on out there are a couple of options:
You invest in your stats normally for a purely physical damage build. Nothing wrong with equipping decent armor, its not nearly as useless as people make it out to be, plus all that weight saved in heavy weaponry goes a long way in having heavier armor options poise and damage reduction. Rolling i-frames are the same, as long as you keep yourself from fat-rolling, you're good. It still affects the run speed and stamina recovery, so, uhm, just experiment.
You go with ~14 VIT and Flynn's Ring - that locks you out of wearing anything but paper for armor but that extra damage is pretty good, because as long as you keep your maximum equipment load at somewhere around 60 it adds 50 damage per hit. On the bright side, you'll have a lot of points left over for VIG.
Dark infuse your rapier and invest into FTH and INT enough to make use of Dark Weapon or Resonant Weapon. The Ice Rapier is probably the best base for this. Resonant Weapon is 2 spell slots so you would need the two slots. Dark Souls 2 very graciously does not scale buff bonus damage from your caster stats, and the Dark infusion scaling on a non-dark base weapon isn't great, so just invest enough stats to cast your buff of choice. Again, this works because weapon buffs add flat damage to your fast attack weapon with a massive counter bonus.
Eh, technically there's nothing wrong with combining 2 and 3.
You'll be dealing greatsword damage per hit on bosses, with a very fast thrusting attack weapon. Besides, as is often the case, thrusting attacks are pretty good in these games in general. Weapon damage in this game would work much better if FromSoftware just added normalization based on weapon attack speed, but hey, it is what it is. With that build you deal a truckload of damage rather quickly and can still respond to enemies without being locked into massive weapon swings.