According to armenologist Edward Aghayan, while creating letter Ց Mashtots did not use any prototype, while Hrachya Acharyan was of the opinion that the author of the Armenian alphabet derived it from the Armenian letter Ծ [ts]. Early examples of Ց look very similar to Յ [y]: the principal difference is the size of the upper semicircle. Later on, the semi-circle was closed, and there were also examples, in which it was written separately from the lower element ( ). Afterwards, letter Ց was used for creating a variant, which got to perform the function of the small letter – ց.
According to one of the existing versions, the variant of this ց – – was used by the creators of the Slavonic alphabet as the prototype of Cyrillic letter . Ց is a prefix, which means “until”: ցպահանջ ([tspahanj] – till called for), ցայսօր ([tsaysor] – to this day), ցտեսություն ([tstesutyun] – till we meet next time). In modern informal Armenian speech, the last word is sometimes reduced to a single ց. Most old Armenian surnames end in – ց: Ghazaryants, Garvarents, Sahakyants, Tonunts, etc. Endings –yants, -ents, -onts, -unts meant belonging to a particular family.
Thus, the surname Simonyants meant “from Simon’s family”, and Changlunts prompted that the founder of the family was born in village Changli (in Western Armenia), etc. With the lapse of time, the endings -ents, -onts, -unts lost their productivity, while the ending -yants lost the last letter “ts”, and the surnames acquired their present-day form with the suffix -yan (Ghazarian, Simonian). However, the “relict” letter ց can still be encountered, communicating the noble, old sounding to Armenian surnames.
See more at Aram Khachaturians "Armenian Alphabet. History and Symbolism" book