Final answer:
The almost yard-long Viking weapon with a decorated hilt and often personalized with a name is the longsword.
Step-by-step explanation:
The weapon that is almost a yard long, has a decorated hilt, and was often given a personal name by its Viking owner is a longsword. The correct answer from the provided options is c) Longsword. Vikings treasured their swords to the extent of forming emotional attachments, further emphasized by the act of naming them. A Viking longsword featured a straight blade with a sharp edge on one or both sides and had a handle or 'hilt' and a cross-guard. Unlike the ceremonial axe, which is a different type of artifact, Viking longswords were practical weapons used in combat.