Re: "8th Gate" Might Guy + Samehada "Greatsword" = The Ultimate Weapon
I thought of this back when Guy fought kisame on turtle island.
I expected him to open the 8 gates back at that time, killing kisame, and himself, leaving Sameheda to Rock Lee as a sort of battle trophy that would be delivered to Lee by Naruto and/or Yamamoto at a slightly later date in time.
That didn't happen.
It'd be dissapointing, but, I'm skeptical as to whether we'll ever really get to see the 8th gate be opened, simply because Guy and Lee are too well liked for them to simply be killed off for any reason.
That all said, A superior weapon, like Sameheda or one of the other mystic swords of the hidden mist village, would be a perfect compliment to a pure Taijutsu user like Lee and/or Gai.
Sameheda would be especially good for Lee because it prevents ninjutsu from being used against him (since it can absorb the chakra powering it), and forces people to fight him using nothing but Taijutsu, which he will inevitably win due to his extreme focus on Taijutsu. The fact that Sameheda is semi-intelligent makes it an even better match-up for him because it means the sword can take care of it's self in a limited fashion.
The real question is what are the conditions that must be met to both use and bond with a mystic sword.
In Sameheda's case, chakra of a certain 'flavor' helps. Bee seems to be have been able to bond with Sameheda in a limited fashion based entirely on the 'flavor' of his chakra, but i think there's more to it then the individual's chakra. If it was that simple, bee would probably use Sameheda to better effect.
If Lee or Guy ever get ahold of 1 of the 7 mystic swords that be awesome, but... i'm not sure that'll happen due to time constraints in the Manga.