Pier Gerlofs Donia's Compass

Origin
Pier Gerlofs Donia (1480 - 1520) was a Frisian rebel leader and pirate. Best known by his nickname Grutte Pier (Big Pier) referring to his legendary size and strength. 19th-century historian Conrad Busken Huet once wrote that Grutte Pier was "A tower of a fellow as strong as an ox, broad shouldered. A natural rough humorist, who through unfortunate circumstances was recast into an awful brute.  Out of personal revenge for the bloody injustice that befell him with the killing of kinsfolk and destruction of his property thus turning him into a freedom fighter of legendary standing."

After death Donia's weapons were discovered to be more like two handed broadswords, however Donia would wield one in each hand. Another allegation was that Donia was able to bent a coin in half using on his thumb, index and middle finger.

Effects
Causes a proportional increase in size, strength and perchance for violence. User eventually grows too large to effectively control their muscles. Has no apparent downsides on those of Frisian lineage.