Appearing to be but a simple decorated greatsword. The steel needing a bit of a polish. But the edge keen and a large emerald set into the cross guard. The blade is actually a wizard caught in a powerful curse, unable to free himself, but capable of thoughtspeech after attuning to a wielder. He may even cast some spells while in combat to help out.
In the Middle Ages, and even up to the early twentieth century, most of Europe's executioners were related: the Sansons and Deiblers in France, the Pierrepoints in England, etc. The reason for this was that, it generally not being socially acceptable to, well, kill people, executioners and their children could, generally, only marry other executioners or their children.
The parallels with massively inbred, Hapsburg-style dynasties are obvious- imagine a rather clever but politically inept satirist noting this, and being sentenced by the latter to a meeting with the former; even worse, imagine a dynasty of deranged and deformed executioners- think Texas Chaisaw Massacre with government funding.