In its early history, Iceland almost faced civil war over the split between pagans and Christians. The issue came to a head in 1000 at the yearly gathering of chiefs (Althingi). The law speaker, Þorgeir Þorkelsson Ljósvetningagoði (himself a pagan), pondered the matter for a day and a night, and came to the decision that Iceland should embrace Christianity, but that pagans could still pursue their religion in secret.
But later, even secret pagan practices became outlawed and during the witch-hunts of 1625-85, twenty-one Icelanders were executed under accusations of witchcraft. Iceland's history of witch trials differed somewhat from those in other countries, in that men were accused more often than women. Most were poor, living in hardscrabble conditions in the Westfjords, and sometimes the accusations were based merely on knowing runes or staves or owning forbidden texts. (One man was accused based on his writings about medicine.) Accusations of witchcraft might be prompted by the presence of illness or misfortune in the village. One woman's illness served to instigate accusations against 6 different men over the course of several years.
The museum included details of the various trials, including a genealogical chart showing the family connections of many of those involved in the cases. There were also descriptions of spells and runes ostensibly used by witches and sorcerers. The spells ranged from acts of destruction (bringing storms to those at sea) to spells bringing prosperity (transforming a human rib into a tilberi who steals milk from other people's sheep and delivers it to the witch's churn). The necropants in the above photo are a prosperity spell. According to the museum, one creates the necropants in the following manner:
"If you want to make your own necropants (literally; nábrók) you have to get permission from a living man to use his skin after he is dead. After he has been buried you must dig up his body and flay the skin of the corpse in one piece from the waist down. As soon as you step into the pants they will stick to your own skin. A coin must be stolen from a poor widow and placed in the scrotum along with the magical sign, nábrókarstafur, written on a piece of paper. Consequently the coin will draw money into the scrotum so it will never be empty, as long as the original coin is not removed. To ensure salvation the owner has to convince someone else to overtake the pants and step into each leg as soon as he gets out of it. The necropants will thus keep the money-gathering nature for generations."
Runes or staves might be written on paper or a scrap of leather, or they could be carved into wood, as with this protective sign.
It was a small but fascinating museum -- the poor lighting made it hard to get good photos, unfortunately, so you'll just have to go visit the museum yourself to see the exhibits. In the meantime, you can find out more about the museum in this video: