I'll put this mostly into comments instead of it being a wall of text. I've scavenged these from a bunch of different articles and videos, plus some help from Kolanaki. Some of it is on the wikis now
Idus set and Idus sword
The gear you get if you take the Idus knight starter class, or by buying it from a nomadic merchant in Liurnia. The sword is found in the open world in Liurnia.
Idus sword: A light greatsword; that is, a sword whose blade matches the length of a greatsword, while only possessing a very light weight due to its remarkable manufacture. A signature weapon in the land of Idus. With cultivated form, one can wield this weapon as swiftly as one might a straight sword.
Silver grooved helm: A silver helm whose expert craftsmanship compensates for its weight. The construction is extremely thin, but the beautifully etched grooves reinforce its strength as protective gear. In the land of Idus, delicacy is no weakness.
Silver grooved armor: Silver armor whose expert craftsmanship compensates for its weight. The construction is extremely thin, but the beautifully etched grooves reinforce its strength as protective gear. The verdant green raiment is given upon receiving the guidance of grace — even if the wearer is but a sapling at present, in time they must grow into ripened gold.
Silver grooved gauntlets: Silver gauntlets whose expert craftsmanship compensates for their weight. The construction is extremely thin, but the beautifully etched grooves reinforce its strength as protective gear. In the land of Idus, delicacy is no weakness.
Silver grooved greaves: Silver greaves whose expert craftsmanship compensates for their weight. The construction is extremely thin, but the beautifully etched grooves reinforce its strength as protective gear. In the land of Idus, delicacy is no weakness.
Silver grooved shield: "A silver shield whose expert craftsmanship compensates for its weight. The elegant grooves render a picturesque scene, recalling the faraway Erdtree's principles. Spread out above shall its many boughs, spread below shall its many roots, till the world entire knows its blessing."
We've got a new country introduced! I'm assuming it's not within the Lands Between since the Erdtree is described as "faraway", but it still clearly has reverence for and knowledge of the Erdtree and Grace, which I don't think we've had confirmed about any non-TLB location yet. Cool little glimpse into the wider world.