Comments: PAT *wǝ; PAK *ḳǝ-ħÁ. In the first part of the AK compound we may possibly see PAK *ḳǝ- 'grow' (unlike Shagirov 2, 135 we wouldn't like to split PAK *ḳač̣́ǝ́ 'short' and find in it's first part the same component; see the etymology of this word). The second component, *ħA, is strangely enough, related by Shagirov (ibid.) to PAK *ħA 'bring, carry'. We would still like to follow Trubetzkoy in connecting the AK and Ub. forms (the ħ:w correspondence is here just the same as in the word for "dog"). However, PAT should have regularly had l-, not w- here; perhaps we should assume that PWC *Łʷ was for some reason split into l and w in PAT (position before different vowels? - there are too few examples to come to a definite conclusion).
In Ub. wa can be also discovered in the word for far (ʎa-wá lit. 'long for feet').