The most capable soldiers of the Imperial Legion are given a chance to prove their skill and loyalty in the Trial of Blades. If they succeed they may join the Phoenix Guard, the most elite force on the Old Continent.
The Guard is under the direct command of the Emperor and serve as his bodyguards and agents throughout the realm. They are often tasked with covert, high-risk missions, which they carry out in small teams (similar to adventurer parties).
The members of the Phoenix Guard are often referred to as the "Immortals" because each member has a vial of blood stashed at their headquarter so that they can be resurrected, should they fall in battle. This practice also makes it hard to gauge the exact number of the Phoenix Guard but most scholars estimate it between 200 and 1000.
The highest ranking members of the Guard are the Imperial Dragon Riders but the group is also known as the Emperor's Hand (5 members, each representing a metaphorical finger). These are independent agents wielding the full authority of the Emperor on their missions (backed up by the fire of a dragon). It is unclear how they are controlling the dragons they ride, but most scholars suspect powerful mind control is involved, perhaps a minor Edict.