He protects you from the Bad Man.
Erich Schreiner’s now-deceased father fashioned him a wooden doll patterned after a medieval knight, made from leftover woodwork scraps discarded in the building of the central church in Silbertal. The body of the doll was formed from a rotund newel post in the shape of a turnip, with arms and legs attached with metal eyelets. While the materials and construction were crude, the piece was carved with intricate detail demonstrating Alder Schreiner’s master skill.
Erich named this doll Sir Egg, and spoke of him as though he was a living character; it was later witnessed that in times of emotional stress, Sir Egg seems to manifest to protect Erich, taking a form vaguely similar to the one imagined by the doll but large and powerful, clad in polished metal armor and wielding an impossibly massive maul. Sir Egg was instrumental in winning the day during the ambush battle against Soramian and Loessian troops outside Silbertal.
Sir Egg remains with Erich now that the boy is older, and his physical form has changed slightly over the years, his armor more pronounced and ornate, and his physique more powerful.