Meriadeuc, or Li Chevaliers a Deus Espees (The Knight of Two Swords), is a thirteenth century French addition to the Arthurian Romances with the hero of the story, the nameless squire of Gawain, inadvertently finding himself and who he is after a series of coincidences originating with the death of the father he never knew he had. A story of self-realization, it is only the moment he fulfills his destiny that he finds out his name, Meriadeuc, was written on the very sword his mother gave him.
Because of his legend's peculiar trait, Meriadeuc defies the common sense of a Heroic Spirit and is always summoned as an incomplete existence, one who must eternally and continually self-actualize with each summoning. His nature is not dissimilar to all other Heroic Spirits though, he has a complete record of what he has done. However, similar to how a Servant's knowledge is "corrected," when they are summoned, as a symbolic existence, Meriadeuc's correction also removes knowledge of his own name as Meriadeuc can only learn his name when he has truly found himself. While this seems not only bothersome, but seemingly pessimistic as well, as if one’s hard work is always reset no matter what answer they find. In truth, one could consider Meriadeuc’s existence a blissfully and naively optimistic one. That no matter how many times one’s hardwork is reset, one will always eventually regain what was lost. It is possible that it is this blind hope and wish that “everything will work out in the end, no matter what” which elevates him into a Heroic Spirit.
Personality-wise Meriadeuc is a natural airhead who fawns over his former master, Gawain. While he is a well-meaning young man, he never actually meant well when performing what could be considered heroic deeds. In that sense, he is a man who heroically charges into tragedy but tragically blunders into heroics. Being the airhead he is, his wish for the Holy Grail is to learn his own name. It is only at the end of each summoning that he understands that this is something that the Holy Grail cannot grant him; rather, something he creates for himself.
While known as The Knight of Two Swords, Meriadeuc is actually summoned with three. There is his father’s sword, the bleeding sword with his name on it, and the sword King Arthur knighted him with. The first two are his Noble Phantasms. It is said that he left the last sword with his mother before taking up the bleeding sword. Meriadeuc rarely uses or even materializes this third sword. After all, it is his proof of knighthood.
Speaking of swords, when summoned, Meriadeuc has no true name. It is until he realizes that the name written on the sword is his own that he shall gain that name. At the same time, it is not until he realizes that his name is Meriadeuc does the sword show the name. It is a paradox that cannot be broken by a third party, after all, his entire existence is based on finding out who he is by himself, for himself. It is both a personal quest as well as a cosmic question. Therefore, it could be said that Meriadeuc’s fight is with himself, not with his opponents.
It is this quest that offers an answer to why his name is Meriadeuc. It is believed that Meriadeuc is the French version of the Welsh name, Meriadoc which was derived from the old Breton name, Meriadeg meaning “sea,” and “forehead.” At the very beginning of the legend, Meriadeuc’s mind is an empty sea, it is only with the arrival of Lady Lore of Cardigan that throws him in his quest. It is the first glimmer of knowledge that pushes one forth to find oneself. However, it is only when one accepts and marries knowledge rather than continuously pushing forth that a quest can happily end.
As an aside, Meriadeuc is a Heroic Spirit who shares many tropes with the other Knight of Two Swords, Balin. If I were pressed, I would say the main difference between the two is Balin’s story is also Lancelot’s, while Meriadeuc’s is also Gawain’s. In that sense, Balin and Meriadeuc would also have terrible affinity with each other.