Appearance: the Imbrian Escutcheon was a medium sized shield that had a very distinct 'valentines' heart shape. It was typically made of Lunar Ash wood, overlaid with a sheet of moonsteel for strength. These shields were not intended for combat and were often ornately decorated, with baroque patterns and images embossed into the metal. Each Shield was a device for carrying the heraldry of a noble Imbrian House, and when conflict or battle arose, these shields were put away.
But the image of a knight carrying a heart shaped shield quickly became the common image of the Imbrian Warrior. This was originally as most art was done in formal and dress situations, and very few paintings or murals were made of the more mundane shields or armors for that matter. It was only many many years after the Imbrian Kingdom was annihilated that the heart shaped shield started being used as a symbol of mockery, weakness, and excessive unmanly chivalry.
Creator: Each of the noble houses of Imbria had their own armorers and shield makers. These craftsmen worked hard to show up their rivals, which lead to a decorative and ornamental 'arms race' between them. The wealth, and importance of each house was demonstrated not just in the quality of materials and workmanship, but in the creativity of the artist armorer who was depicting the house heraldry.
The Royal House of Imbria had a unicorn as it's heraldic device, and it's master shield maker actually fashioned the unicorn on the shield out of several gathered unicorn horns. The shield had no specific magical powers and proved useless when the Kingdom was destroyed. It was destroyed, and only remains because of one writing that survived a critique of the wasteful use of unicorn horn and a tersely worded question asking if the unicorns minded that use of their horns, and if they were given willingly. Such were the excesses of Imbria in it's final days.
History: The Heart shaped shield was only one of many contemporary designs of shields on the Moon. It wasn't until the Imbrian Dynasty was forged that the heart shape became widespread. The Royal House carried on the tradition, and the lesser noble houses that had allied with the Queen followed suit, discarding their previous basic shield designs to take up using the heart shape.
These were formal and dress shields, the sort worn by knights with their parade and dress armors. The top of the shield has a fundamental weakness in the cleavage shape and the lower section is somewhat lacking in terms of protection. Regular round, oval, and other shaped shields were used in times of actual war. The later ornamental shields rapidly gained weight, along with the precious stones, other metal inlays, and other exotic materials. Some of these decorative shields were easily fifteen to thirty pounds each.
Specifics: The Imbrian Escutcheon is a decorative shield. It is a status symbol and most are treated as objets d'art. The best place to find one is in a dragon's forgotten hoard.
There are exceptions. The Royal House of Imbria retained the use of the Heart shaped shield, in an unornamented fashion. The early Royal shields were of excellent make, and were imbued with strong magics and defensive spells. At least one of these heart shaped shields survived the trip to Earth. The shield has found it's way from one mercenary, to another, one hero to another, and one adventurer to another. Some have been heros, some villains, and others merely did what they had to do. The only thing they had in common was that each was a woman.