if you have everything, they “should” be a cakewalk, since there are never more than 2 at a time and they only need like 6hits each at that stage
possible fight strategy
Strength charm, shaman stone, dreamwielder, -rest for kicks and giggles (or whatever you fancy, quickslash can even be handy if you use nail alot)
each Watcher starts with temporary pause stance, which lets you dream nail to near full mana or full if you are quick
then their first moves will always be melee if you are standing close enough to get the engage started, pretty much providing you 3 free hits, 1 on starter, jump over as he starts his attack -nail slash down, and free hit in the back as they have a fixed moveset.
With pure nail and Strength charm this almost cuts their hp in half, if you don’t make all 3 hits, don’t worry, just bait their engage and jump over and get the free hit in the back
when the “balling” then starts, you evade on vertical, dash to either side, vertical bounces don’t sway much. and wait for them to unfold, for the horizontal rolls you spam that fireball like there is no tomorrow as long as you know both get hit, this is straight up free dual dmg, as it will hit both, dmg them while balling (nail dont dmg during ball only spell does) and depending on their trajectory they can even get hit by 1 fireball multiple times each.
rinse repeat when they unfold, bait attack, monach wings/jump over (or even shadow dash through if you are comfy with the cd) and stab them in the back
should you get “cornered” by 2 or feel uncomfortable during vertical bounce you can ground slam, for dmg and temporary iframes, and then maneuver back to the “get them to swing, jump over - stab” spam spells
as you notice i say spam spells, with Shade Soul (or even the other upgraded spells landing hits, you dmg them immensely, and due to their paused stance on wake up you can get free soul to spend on those spell spam each fight segment
they have around 200hp each, your nail+strength does 32dmg your Shade Soul +shaman stone does 40 dmg(and ofc penetrates/can hit both), so that’s like 3nail hits +3fireballs per watcher and dead(a good groundslam does like 80dmg with shaman stone btw). Should be “easy” enough to do with the free mana you can get from Dream wielder wakeup stance dream nailing each segment, and then ofc trying to line the fireball up to hit both watchers per segment leaving very few actual nail hits left with your full upgrades
as long as you can get comfy with the “bait” their attack windup and jump over and slash them (either down or in back) you should have a fairly quick fight with all those upgrades