MMORPG.com's own V D writes this helpful guide to Blacksmithing and Tailoring Runic Bonuses in Ultima Online.

Crafting an item using a Runic Crafting Tool results in a random magic item property (or properties) being added to that item. The number of properties that are added to the crafted object and the minimum and maximum % intensity of each property are determined by the type of material the Runic tool is constructed from.

Read Blacksmithing and Tailoring Runic Bonuses