Oh yes, there goes another one.

For thousands of years, Imubia was the greatest human dominion in known galaxy. It dwarfed all the other human factions with over one thousand of reasonably prosperous colonies.
The size of Imubia created many problems. Due to information lag, colonies further from the capital were notoriously underdeveloped, basically dividing the country into two rings - highly civilised Inner Ring, and backwards Outer Ring.
The split became even more apparent in the first half of the seventh millennium PRB (Post Rain of Blood). Core worlds of inner ring were attacked from the inside, by the entity known as the Plague. The capital has fallen and the ruling body, the Senate was completely wiped out. Imubian Outer Ring, ravaged by Red Hammer rebellion, pirate raids and war with Shata'lin seized the opportunity and declared independence, while the Inner Ring was still recovering from the loss of the capital.

Despite initial losses, Republic retained most of its production capacity and, even more importantly, science and technological divisions.
The shock after loss of a capital quickly passed and the main military council quickly formed the new Senate. Republic only by name, Inner Ring is effectively under military rule out of sheer necessity.
The Plague that ravaged the capital was a threat of unimaginable proportions - and infectious, sentient disease able to spread both by physical and psionic means.
The Plague proved to be a massive threat - able to infiltrate and infect the entire sectors as well as take on mighty Legions directly. At this stage, military prowess became a matter of survival. Soon after declaring themselves a separate entity from the Empire, Republic ceased all hostilities against most other nations, swallowed own pride and asked for help. Other factions quickly recognised the threat, and while they were not really willing to aid directly, they decided to aid the Repiblic by sending resources, scientists and by sharing some technologies.

The Legions of the republic had to be completely re-made. Conscription was no longer an option - poorly trained men were nothing more but food for the Plague. New Legions needed superior soldiers, with good training, superb equipment and strong will.
Legionaries of the Republic are expertly trained and heavily indoctrinated. They are fanatically loyal to the ideas of the Republic - recruited from the patriots of the former Core Worlds. They are no conscripts, but fully fledged professional soldiers trained to fight both the Plague and any other threat.

Their equipment complements superior training. Legionaries of the Republic have at their disposal some of the best gear their country could provide.
Their standard issue weapon is Type-5 Sagittarius battle rifle - nicknamed "The Brick" by the legionaries. Unlike the Imperial counterpart, Sagittarius is a high calibre, heavy battle rifle. It fires heavy, armour-piercing-incendiary caseless rounds, either in semi-automatic mode or in three round bursts. The magazine holds up to 20 rounds. The weapon is incredibly accurate and heavy firepower is needed against enemy as the Plague - a monstrosity that feels no pain and lacks vital organs - the weapon needs to shred and scorch the flesh to slow the regeneration of the beast.
Sagittarius is a semi-modular weapon and features many possible undeslung attachments - from shotguns to grenade launchers.
The weapon was designed with nearly complete disregard for ergonomics - it features heavy recoil, is heavy and rather rather inconvenient to handle - however, all these flaws are compensated by the power armour.

Type-3 Power Armour "The Immortal" is based on the Mk. 3 Aries (or RAM) battle armour pre-dating the Split. It is by far the most sophisticated power-armour used by any human faction. External plating is made out of metallic composites, while the inner layers and moving parts are made of popular and versatile fibro-steel. The armoured is fully powered - the soldier wearing the Immortal is nearly twice as strong as normal with almost no loss in reaction time, thanks indirect neural links, basically reverse-engineered from older, captured Shata'lin armours. The suit is completely airtight and can be used in any environment, including space without further modifications. Life support systems monitor physical and mental state of the user, while advanced comms provide each soldier with complex data about positions of allies, enemies, current orders and so on. Optics provide multiple, standard-issue filters.
One of the most important features of the armour is a set of psionic inhibitors that make the user more resistant against direct psionic attacks and telepathic intrusion - allowing the to fight the Plague longer without risking the infection.
The armour is shaped mostly like the traditional Legionary armour - a relatively simple, segmented plated suit. One notable feature is the face plate - shaped to resemble the skull, both to demoralise potential enemy - obviously this feature is quite useless against the Plague itself - some soldiers that were sent to the Plague front treat this mask as sort of the sick joke, rather than a feature.

Speaking of Plague - the disease spreads through physical means as well as psionics - one of the most important features of the armour is a set of psionic inhibitors that make the user more resistant against direct psionic attacks and telepathic intrusion - allowing the to fight the Plague longer without risking the infection.
Against physical infection the armour has some gruesome features meant to prevent that. Brutal they may be - they saved the lives of countless soldiers. When life support systems detect that the limb area has been perforated by the Plague and the users tissue had direct contact with the infected, it automatically severs and incinerates the limb. As brutal as it sounds, Legionaries generally find it to be a fair trade - it is better to lose an arm or leg than entire life.
In case of mortal wounds - the armour is set to initiate incineration of the entire body - but this system does not always work - such wounds usually mean being torn apart anyway.

Legionaries of the Republic are usually deployed in similar fashion to Nhilar Abhair Corporation troops - in small squads of 8 men and AFV or dropship support. A squad is made of two identical sections, 4 men each, all armed similarly, but with different underslung attachments for their weapons - a leader with a shotgun attachment, 2 riflemen with grenade launchers and sharpshooter/scout with marker light and additional comms equipment.
Grenades and specialist weapons are issued separately, depending on type of deployment.