Naruto Databook 4 "Naruto Jin no Sho"

So basically it just talks about how Mifune trained himself heavily and eventually his own body became like a Meitou (a legendary sword). Than it talks about how he is a great ruler of the Samurai and how he finally managedo to defeat Hanzo by piercing him with his faith, via his Meitou sword Kurosawa. Than talks about peace and all that garbage.

Nothing really there about Mifune's skills or abilities besides this:

Mifune's fast stroke of the sword, the shinobi's seals are bound exposing a chink in their armor (weak point), which is a godsend!! Mifune's Iai technique increases the speed of his slashes (is basically what it says).

In an ultra heavy massive sand prison one bids farewell to the physical world for all eternity.

The body's movements are stolen by a massive amount of sand, it's a fuuin jutsu. It's characteristic is a large pyramid-like shape, it's extraordinarily difficult to escape. It's immensely effective even against formidable kage-class enemies. A large quantity of sand mercilessly coils around the enemy. To add Shukaku's sand body and curse seal, the seal becomes more secure. The air can not penetrated, a perfect grave stone of ultra high density sand.

A person is imprisoned in a sand pyramid, that day it was seen twice. A sand prison of extreme hardness.

Sharp blades of vacuum breath force cut down the enemy.

Danzo's strong point is to use a variety of Fuuton. From the mouth one spurts out sharp breath, like the Kamaitachi*, at the target's body, chakra defenses are torn to pieces. On occasion "Shinkū Renpa" released by a large breath that is vomited out, the Susanoo defense is succesfuly destroyed by a disastrous impregnable attack that's like a Kamaitachi herd.

Shinkū Renpa releases a kamaitachi towards the opponent's body, chakra is cut down! A animal can be summoned to utilize it's power, which increases it's strength.

*Kaimetachi refers to how in myth there were three weasels that wiped up whirlwinds capable of cutting through everything.

The target is shot at by sharp blades until their breath ends

In a moment ones breath is vomited out, the jutsu begins by kneading chakra into a bullet. To begin with short breaths results in a machine gun, it becomes possible to turn the opponent into a bee's nest (weird analogy I know, but I think it means the holes in a bee's nest, that's the best I got people). To begin with breathing in heavily results in "Shinkū Taigyoku", a gigantic sphere air bullet that is like having a bazooka in ones artillery. It boasts the power to blow away the targets body.

To vomit out short breaths in succession is "Shinkūgyoku". To breath repeatedly at one time in rapid succession, the body is pierced through.

To take a great breath in is "Shinkū Taigyoku. The power to blow away the whole body.

Taijutsu, hiden
Image from Volume 55, page 191

Chakra is built up within the body and released from both hands all at once! It is a gentle fist art of Neji’s that delivers a critical blow to close-up enemies. It can also be used as a counter against attacks from the rear.

The secret techniques of the Samurai sparkle on the battlefield -- all to sharpen their blade

The Samurai who protect Iron country, they spend most days aiming to devote oneself to the study of sword techniques. To directly attack the enemy they study how to most effectively use their body as a tool in such a way that their movements are quicker than those of most Shinobi (? I think, this was a tough one), additionally they are determined to polish their blades through sword technique mastery. Now in the present time, they test out their katana skillfulness on the stage of the Fourth Great Ninja War!! It's their destiny... When released on the battlefield their sword techniques achieve maximum brilliance, their chief Mifune is a general, they were brought up through multiple wars, and the power of the Samurai spread to many nations (I think this means many nations heard about their strength). By means of their military arts, they disciplined others in the existence of the Samurai of the Iron country!!

Sword techniques that have been handed down in the Iron Country. The skill of the Samurai is released, steel bisection.

"Issen" (or Flash) - is what Mifune announces his technique as in the posted panel and sets up the context of the next bit of text -

Speed of light sword slash flies and assails the enemy! A single blow from the sword techniques of Mifune's Meitou (legendary sword) Kurosawa comply with this!! (I.E. making the force of the slash fly by moving the sword at the speed of light).

T/N Speed of light yeah, oh my fucking hyperbole.