interesting.... Itachi vs. all of the origional swordsmen...
I think that the swordsmen would win.
Executioner's Blade (Zabuza)- This guy is know for his silent killing tech., strenght, and his sword ability to gerneate..... though not much w/o Hiku
Shark Skin (Fuguki Suikazan)- Slient Killing tech., assumed chakara absorb, sword can eat chakara, sense it, and fuse with sword to expand abilities.
Twin sword (Mangetsu Hōzuki)- Hydration technique master, Molds chakara to become a hammer (though it can be plasible for it to become any type of weapon user desires), master swordsmen, and silent killing tech.
Thunderswords (Ameyuri Ringo)- Silent killing tech., assumed lighting and water ninjitsu, two swords that can cut through anything
Helmet Splitter (Jinin Akebino)- assumed Silent killing technique, assumed to be physically strong, and sword can pierce any defense
Sewing Needle (Kushimaru Kuriarare)- assumed silent killing, sword can sew together multiple people, assumed fast and very accurate because of this
Blastsword (Jinpachi Munashi)- Silent killing technique, sword explodes, and he has an eye patch and thus far EVERY character that has an eye problem has it replaced with a dojitsu = assumed beykugan or shariengun;doughtful rinnigan.
Itachi- MS= Tsukuyomi, Amaterasu, Susanoo
he is very fast and intelegent, proficent in multiple fire ninjitsu, great in tiejitsu
Ok so now problem for itachi, low chakara compaired to the entire 7 swords, MS abilites hurt him and eat up his chakara. This is a big problem because he will be forced to rely mostly on these because it is 7 on 1. His best bet is to use a combination of Tsukuyomi and Amaterasu because Susanoo is just a waste of chakara. Why? becuase in full form it can be absorbed and pierced by both blunt and lighting and in skeleton form he can be easily hit by the sewing/ hydration technique. Additionally if the explosion sword can see chakara then the seven swords knows percisely how much itachi has to work with
So using a mass chakara drainer like that would be a waste unless he went out strong with the sealing sword and managed to get most of them. But it would be wiser if itachi used his other two techniques because he could disrupt there cordination with genjitsu and attempt to take them out one by one. But in the end entirely relying on these MS techniques have a limit and physically hurt him every time he uses them. If the seven swords just attack from a distance hiding in the mist I think Itachi is done for. Simply because of the multiple combinations of the 7 and major chakara diffrence. One on one itachi wins agianst any one of the 7 but together itachi can't win