-Versatility of Earth Grudge Fear Transformations v1 and v2
These insanely powerful dark thread transformations are often overlooked when considering Kakuzu’s moveset. To different degrees of effectiveness respectively, they grant him superiority in close combat which Kakuzu could use to his own advantage by:
-Overwhelming Kisame with a sheer amount of assaults from his threads
-A restraint mechanism which could be combed with powerful ninjutsu projectiles from his masks
-A pseudo form of flight by swinging from one part of the terrain to another
-Use them as prosthetic flexible limbs to hold off Kisame's own attacks whilst simultaneously attacking himself
Kakuzu's Earth Grudge Transformation v2
Kakuzu was shown to use his v2 (Long range) transformation to perch himself on higher parts of the terrain, which could be used as a escape mechanism from Kisame’s Water Dome technique or even as shielding himself from large waves of water.
Kakashi also commented on the threads being far too fast
to escape from when he was initially caught which could potentially mean it could act in a similar way to Mifune’s laido technique
, granted to a much lesser extent, to prevent Kisame from forming handseals and using his larger scale ninjutsu attacks.
When merged with his masks, Kakuzu has shown that they retain the ability to act on his command, suggesting that he could engage Kisame in Taijutsu whilst using high scale ninjutsu which would be impossible for Samehada to absorb completely. I’ll return to this specific point later on.
Kakuzu's Dark Threads Acting like extra Limbs for combat
Kisame’s reliance on Samehada could be exploited as a severe weakness by Kakuzu, his transformation would enable him to restrain the sword and succeed in either landing a direct hit on Kisame or separating him from his sword which he could seize as a opportunity to land a fatal katon/fuuton infused blast which Kisame wouldn’t be able to regenerate from due to his separation from his sword.
On a final note, Kakuzu has shown time and time again the lethal purposes his dark threads could be used for, primarily through choking his opponents to death on repeated occasions, and ripping through their bodies with this threads
, deep enough so he could integrate their heart into his own system instantaneously. This could possibly suggest an alternative use of Kakuzu's threads to make lethal hits on Kisame, amputate whole limbs or even kill Samehada.