Comments: PAK *čǝ. Kab. q:ʷa-š < *q:ʷá-čǝ 'son+brother', cf. Ad. q:ʷaš 'own brother, brother having the same family name'. Reason for voicing *č́ʷ > *č́ > ǯ́ in the Ub. form is not quite clear (cf. perhaps the irregular voicing in plural in PN?).
PAT *aš́a 'brother' should be kept separate and traced back (together with Ub. -ʎa) to another PWC root, *ʎ́a q.v.