Etymology of terms.

[Cilia]

OK, here we go.

GEROLT'S MASTERWORKS
Burtgang: Better known as "Blutgang." Sword of Heime, a legendary Germanic hero.
Glanzfaust: "Shining Fist," roughly translated from German.
Rosenbogen: "Rose Arch," roughly translated from German.
Yagrush: Mace of the pagan god Baal.
Laevateinn: an obscure weapon from Norse mythology. Believed to be a staff.
Vajra(s): means "thunderbolt" or "diamond" in Sanskrit. A type of weapon, as well as the name of a mythical king in the Mahabharata.
Arondight: Lancelot's sword from Arthurian mythos. (It's just an oversized Burtgang, c'mon SE...)
Sirius: the brightest star in the night sky.

Additionally, a lot of bosses and flavor for the "Shadow of Mhach" line borrows from the Ulster cycle of Irish myth, though not exclusively.

SHADOW OF MHACH
Cuchulainn (Cu Chulainn): a hero of the Ulster cycle. Originally named "Setana," he took the name "Cu Chulainn" (Culann's Hound) after killing... Culann's hound and taking the position in penance, until a replacement could be raised.
Echidna: a half-woman, half-snake monster from Greek mythology. Mate of Typhon.
Arachne: a woman from Greek myth turned into the first spider by Athena for her hubris.
Forgall: a character from the Ulster cycle. Suggests Cu Chulainn go train under Scathach to prevent him from marrying his younger daughter Emer while the older is still unwed. When Cu Chulainn returns he still refuses to allow him to marry Emer, leading to Cu Chulainn storming his fortress; Forgall falls off the ramparts in the attack and dies.
Dun Scaith: fortress of Scathach from the Ulster cycle.
Ferdiad: Cu Chulainn's foster brother from the Ulster cycle. Possessed an impenetrable hide as a counter to Cu Chulainn's Gae Bolg, but was nonetheless slain with the spear. (Don't ask how.)
Scathach: warrior woman from the Ulster cycle who trained both Cu Chulainn and Ferdiad. Presided over Dun Scaith and the original owner of the Gae Bolg.
Connla: Cu Chulainn's illegitimate son, raised by his mother alone. Killed by his father, who learned his identity shortly after Connla's death.

... and...

Cait Sith: a type of fairy from Celtic myth. Also believed to possibly be a witch capable of transforming herself into a cat nine times.