GWLADUS (standardized modern form)
A late addition to the "Hanesyn Hen" genealogical tract, appearing in only a few versions of it, mentions another daughter of Rhydderch Hael named Gwladus, who presumably would have a similar calculated date to her sister, i.e. late-mid 6th c.
Gladus - Cardiff Ms. 25, 1640
Wladvs - Peniarth Ms. 129, ca. 1500 (and other mss. of later date)
Given the late date at which this was inserted into an existing tract, the historic reliability is uncertain. Bartrum (WCD), however, lists other women with this name of a similar era. Among the "core group" of Brychan Brycheiniog's children (ca. late 5th c.) is a Gwladus, mentioned variously as:
Gladus - De Situ Brecheniauc (Cotton ms. Vespasian A xiv, fos. 10v-11v (ca. 1200) text perhaps a century earlier
Gluadus - Cognacio Brychan (Cotton MS. Domitian I, fox. 157v-158v) ms. dated 1502-55, copied from a ms poss of the 13th c. (presumably a scribal error for Guladus
Gwladus - JC MS 20 written late 14th c., copied from ms ca. 1200
Gwladvs - Plant Brychan
In addition, Llywarch Hen is said to have had a daughter by this name, but she appears only in a late addition to his material (ca. 1600) (Bartrum EWGT).
Although the name Gwladus is sometimes equated with Latin Claudia, there is unlikely to be any linguistic connection. Rather we should look for connections with the element gwlad "land, country" in other personal names, perhaps including the feminine name Gwledyr, as well as common nouns such as gwledig "ruler" etc. The most simple analysis of Gwladus would suffix this root with an adjectival ending -us (originally occurring in borrowings from Latin with -osus, but then reanalyzed as a productive suffix in Welsh), alternatively there is later evidence for -ws as a diminutive suffix and the early forms with u would be consistent with this, although later retention of u argues against it.
If we accept the derivation from gwlad and the adjectival suffix, then we can postulate a mid 6th century Latinized written form Vlatusa and a spoken form something like ['ul-ad-us] or, in English syllables, "OOL-ahd-oos".