Royalty

Are you sure? I thought the grenade was first used in the Ming Dynasty, King Louis XIV formed the first regimient of Grenadiers in the early 17th century, and the British equivalent was formed, following their defeat of the French Grenadiers close to Hougoumont Farm, during the Battle of Waterloo.

I suspect this pre-dates the colonial settlement of Grenada.

In fact they're from Granada. Arab traders were first to get in direct contact with Chinese under Yuan dynasty and acquire gun powder. "Chinese snow" was packed into the hollowed local fruit pomegranate (pomme-grenade) and used against Crusaders in the Levant.
Grandada, hence Polish granat.