You might want to work with the other users of WoWWiki in expanding it.
"The runeblade is an extension of your being. A death knight cannot battle without a runeblade." - Instructor Razuvious
Runeblades are usually swords inscribed with magical or demonic runes that grant certain powers to the wielder. All high-ranking death knights wield their own personal, named runeblade, called vampiric runeblades. However, runeblades are not unique to the Scourge. Although Frostmourne was undoubtedly the most prominent runeblade in existence (Kael'thas' Felo'melorn being the second), there are quite a few additional ones.