Damn dude you are on to something. I want it more gladiator style, since Barristan lacks armor and his shield, the Unsullied form a phalanx with Barristan in the rear. Archers appear and send a volley killing some unsullied, an attack from the sides and rear, Greyworm orders a shield circle with Barristan in the center. some arrows find non lethal marks and the unsullied hold their shield wall despite the injuries.
The first wave of SOH attack, most are impaled upon spears, some fly over the shield wall needing to be killed by Barristan's long sword, while greyworm plunges his spears bottom (forget what this is called) into faces and hearts. Grey worm yells commands to move back to the exit, but progress is slow the arrows still fly and a few more unsullied die, but they continue to fill the gaps in the formation while chanting and moving as one.
All of a sudden (doors close, more SOH, or my favorite oil is dumped and set on fire.) they cannot get out that way. But alas its an advantage, they do not have to cover their rear with so many, a full circle turns into a rectangle, SOH attack again from the front and die impaled upon the spears, the phalanx shows why its so deadly moving forward. The SOH hesitate to do another frontal attack, they stand their ground letting the archers do the work while some small javelins are thrown.
They unsullied have no where to go but forward. The have to attack and force their way out, there is no other alternative. Grey worm gives the command and the unsullied do what is a last resort the front rank throws their spears, the then the second. They draw swords and attack, the first rank smashes into the ranks of SOH with their shields cracking bones and knocking many SOH over . Archers kill even more and grey worm is wounded badly and a few unsullied form a shield wall to protect their commander.
Barristan yells commands in valayrian, he takes over and the unsullied follow. He can no longer stand by while unsullied die protecting him, he picks up a shield from a fallen warrior just as the first rank of unsullied as finally cut down.
His long sword is vastly superior with room, while the short sword of the unsullied echos discipline and close quarters. They have to attack, the fire is preventing a group of SOH from entering the battle but not for long, unsullied cannot maintain their phalanx formation with locking shields, this leaves them open to SOH with their knives and short swords. The unsullied armor protects from many stabs and slashes, but they are overwhelmed dragged to the ground and butchered with throats and leg arteries being severed.
SOH are breaking, they are not as disciplined and the plan was a quick overwhelming attack. the unsullied are advancing over the bodies of friend and foe with barristan in front unarmored cutting down many SOH, this badly demoralizes the SOH . Then a purple crest is seen in the rear ranks of the SOH, a SOH dressed in full plate and fine silks is point his sword forward and yelling commands. He leads the SOH, edging them on, the plan was to kill Grey Worm, and they believe they have succeeded, but they see Barristan unarmored. This is more than they could have hoped for, a prize worth continuing the slaughter.
Barristan takes a arrow from the rear behind the wall of fire and it hits his left shoulder. This cripples his shield arm and his shield drops lower, he can only raise it with horrible pain. Now he truly is naked in combat. The full plated SOH notices this, and some of his men are still running despite his command, he most stop a rout from happening and killing a leader of the false queen will put the fire back into his men. Barristan still kills one after another, the purple crested SOH advances towards the wounded old knight. He quickly kills a unsullied showing he is a well trained warrior, a knight in all but title.
Ser barristan shield is dropping lower and lower, and the purple knight makes his move. A crashing blow is blocked with Barristans shield, a parry, barristan darts to the left side stepping a blow. He must use his mobility, its the only advantage he has. Another arrows hits Ser barristan in the calf, he winches in pain, an opening is available, and to late raises his sword to parry a blow, the knight finds his mark and severs Barristans sword hand. Barrsitan stumbles back screaming in agony, the purple knight cuts down one more unsullied and next comes to Barristan. The lord commander is tired, he is old, he is badly wounded, thus its time for the coup de grâce. Barristan moves faster than the enemy expect and thrusts the bottom of his shield into the throat of the attacker crushing his windpipe, the SOH leader with all his splendor collapses gripping his throat. Barristan crawls with a stump shooting blood, his shield dropped, and he draws his dagger from his belt with his left hand and drives it into the eye slit of his defeated foe. a scream of agony bellows out from the SOH armored warrior.
The SOH break and run. They are victorious, or are they? Barristan is lying dead untop of the Meeren knight with his dagger handle protruding from the SOH helmet.
Greyworm held up by the surviving unsullied says.
"take this ones body."
Dany is later shown the helmet of the defeated SOH, with Barristan's dagger still plunged deep in the metal.
Later songs are sung about an old knight called Ser Barristan the bold, whose many deeds were repaid with treachery. A sad song, but the ending speaks of an epic battle pitting the unarmored one handed-old-hero verse a skilled, but false knight. Ser Barristain defeated him with only his dagger.
He was cremated by the fires of Drogon the black, and in the white tower the helmet of the SOH sits with Barristan's dagger still embedded in the steel. It was said Ser Barristan's hand could not be removed from his sword. Even in death he was always ready to defend the queen. stories are told to little children to be honest in their dealings and with the crown, or the lord commanders sword will find them in the night to dispel justice.