―Queen Elinor to King Fergus when he first presented young Merida with her first bow
Merida's Bow is Merida's primary weapon of choice. A recurve bow, there were in fact at least two bows she was seen in possession of.
The first was given to her by her father, King Fergus, on her sixth birthday, perfectly sized for her diminutive height and most likely for her youthful and inexperienced draw strength.
The second seen—although she probably had more as she was growing up—was the one she owned at sixteen and for the Highland Games. It is unknown if it too was given to her by Fergus.
Merida's first bow was a simple thing. A recurve, it was nearly as tall as her six year old self. Wooden, it had white limbs with a brown leather-wrapped riser.
The second bow seen in Merida's possession looked very much like the one her father gave her as a child, and why many think it was the same. This bow was apparently relatively new to her as she was seen etching a stylized eagle into its belly, the side facing the bowman, something she would have done before had she had it any length of time. It too was just shy of her own body height.
However there were extras which reflected Merida's dedicated proficiency in archery. Another recurve, this one had intricately carved scrollwork on the back, or side facing away from the bowman, and was outfitted with bowstring dampening disks at the nocks of both upper and lower limbs. A vital hunter's accessory, the disks serve to dampen and quiet the twang sound of a released string striking the limbs. The disks appeared to be adorned with the sword-and-interlocking-circles crest of Clan DunBroch.
Merida's love for archery is first seen when at six years old she wanted to try King Fergus's full-sized bow as it sat on a table. Instead he presented her with her own child-appropriate sized bow as a birthday present, much to her mother, Queen Elinor's, disapproval. Merida, while being instructed by her father, tries firing arrows with her new bow, but missed every shot until the last arrow flew into the forest and Elinor tells Merida to go fetch it. While she is gone, Elinor scolds Fergus for giving Merida the bow, whom she wants to be a proper lady.
Ten years later, on one of the rare days when there are no lessons, she goes riding on her horse Angus. She uses her bow to shoot arrows at targets she had previously set up in the forest, hitting them all as her archery skills have greatly improved.
On the day suitors arranged by her parents are presented to the princess, Elinor proclaims that only the firstborn of the great leaders may compete in the games, which gives Merida an idea of how to get out of marriage: she decided to choose archery and compete for her own hand in the Highland Games.
When the competition begins, Merida hides her bow and arrows behind her throne before sneaking off to appear on the field, declaring she will shoot for her own hand. Ignoring Elinor's protests and orders, she strikes the bull's-eyes of targets of the first two suitors. When she shoots an arrow through the full length of Wee Dingwall's arrow and the target itself, she smiles… until she turns to face her furious mother, who drags her into private. During the following argument about what constitutes a proper lady, Elinor called her a child before throwing Merida's bow into a lit fireplace. After Merida tearfully runs away, Elinor quickly fishes the bow from the fire, its bowstring snapped, feeling horribly guilty as she too begins to cry.
Later when locked in the very same room while Fergus went off in hunt of the bear Elinor had been turned into, Merida apparently found and restrung her bow, a little singed but still serviceable, as she had it at the Ring of Stones for the final fight against Mor'du and the restoration of her mother's humanity.
In Once Upon a Time it was Fergus' first war bow and he gave it to his daughter, as she was taking part in her first war and battle and to keep her safe. After Fergus was killed it became Merida's reminder of him, as the bow was the last thing he gave her; she had tried to use it save her father's life, but the arrow she shot from it only hit the killer's cloak. Zelena uses her magic on the bow, so she and Arthur can find the Helm.
It is unlikely that Merida had only the two bows. As both her body and archery skills grew, she would have gone through several in her lifetime, both for length and draw strengths.
While recurves are different from longbows—due to the specifics of their construction—most are nonetheless classified as "longbows" for being about the height of the user, which is the primary difference between short- and longbows.
Except for the recurving of the limbs, Merida's bows were crafted the same as longbows as they were of one piece with a round cross section.
Mounted bowmen typically use shortbows so they can easily and quickly switch sides of the horse while drawing in battle. The bow used by Young MacGuffin is representative of a calvary shortbow.
That Merida can expertly shoot with a longbow from galloping horseback showcases exactly how proficiently skilled an archer she is.
The splitting of one arrow with another is a trope used in many fictional archery stories which apparently started in the 17th Century with the literary legend of Robin Hood. Although partial splits have been documented in real life, the feat of a complete splitting nock-to-head has never been substantiated. When partials happen in real life competitions, it is ruled as a draw.
The first bow Merida gets in the video game is her main bow.