The STEDT lists the Chinese word for ‘hand’: 手, Middle Chinese syuwX (something like [ɕjow] in tone Shang), under its etymon #731 PTB *g(t)syəw-k/ŋ WING / HAND: if true, this would make the Chinese word a cognate of Written Tibetan gshog ‘wing’; of Bantawa chuk ‘hand’, Nung tshuŋ⁵⁵ ‘arm’, Sangtam khyo ‘wing’, etc. The STEDT mentions Chou Fa-kao’s PST reconstruction *tśəw as a precursor (Chou 1972). Matisoff (2003:199) gave *tsyəw. The STEDT adds a root preinitial *g- before the affricate, this now restated as optionally fricative. Two alternating ‘suffixes’ -ŋ/-k, without any stated function, are also added as optional fixtures. Thus the STEDT etymon #731 contains any word in a ST language with a high rounded vocoid preceded by a sibilant onset, or a velar stop onset, or both simultaneously, and followed (or not) by -ŋ or -k, meaning ‘arm’, ‘hand’ or ‘wing’. The net is cast wide.
On the Chinese side, Unger (1995) and Zhengzhang (1995) independently argued that the Old Chinese initial of 手 included an alveolar nasal: *sny- (Unger), *hnj- (Zhengzhang). The evidence is summarized in Sagart (1999:155), where 手 is given as OC *bhnuʔ. Wang Li (1982:231) had already noted that 杻/杽 MC trhjuwX ‘shackles, handcuffs’ must be a cognate of the word for ‘hand’: the phonetic in the first of these characters is 丑, whose OC onset definitely included an alveolar nasal. Moreover the archaic graph for 丑 is similar to 又 ‘right hand’, with additional strokes representing nails or claws.
Sagart (ibid.) studied the word-family of 手 in Chinese on that basis. He accounted for the phonological alternation between 手 and 杻 by treating the former as *bhnuʔ and the latter as *bhnruʔ, with plural-object <r> infix. Evolution from *bhnruʔ to MC trhjuwX is regular. Another member of the word-family is 狃 MC nrjuwX ‘claws’: this is given by Sagart (ibid.) as OC *bnruʔ (also with plural-object <r> infix). In the Baxter-Sagart system (2014), these forms are reconstructed as 手 *n̥uʔ ‘hand’, 杻 *n̥<r>uʔ ‘shackles, handcuffs’ and 狃 *Cə.n<r>uʔ ‘claws’ —there is in Hakka and in Hmong-Mien indirect evidence for a voiceless preinitial consonant in ‘claws’.
The Min dialect forms with tsh- initials—e.g. Xiamen tshiu 3— are shown in Baxter and Sagart (2014:93) to reflect OC *n̥- regularly. They do not argue for etymological connections to affricates in other ST languages. Consequently all the etymological connections proposed in the STEDT between 手 and the rest of etymon #731 are spurious.
手 does have a clear cognate in Written Burmese hnyûi ‘finger’, however. That form is not listed in STEDT #731. The meaning ‘finger’ appears to be the older one: a change from ‘finger’ to ‘hand’ is common, while the reverse is apparently not attested (Heine 1997): we probably have a PST word for ‘finger’, something like #C̥.nuʔ ‘finger’, evolving in OC to *n̥uʔ ‘hand’, Written Burmese hnyûi ‘finger’.
Baxter, William H. and Laurent Sagart. 2014. Old Chinese: a new reconstruction. New York: Oxford University Press.
Chou Fa-kao. 1972. Archaic Chinese and Sino-Tibetan. Journal of the Institute of Chinese Studies of the Chinese University of Hong Kong 5.1:159-237.
Heine, Bernd. 1997. Cognitive foundations of grammar. Oxford: Oxford University Press.
Matisoff, J. 2003. Handbook of Proto-Tibeto-Burman. Berkeley, Los Angeles, London: University of California Press.
Sagart, L. 1999. The Roots of Old Chinese. Current Issues in Linguistic Theory, 184. Amsterdam: John Benjamins.
Unger, U. 1995. Finger. Hao-Ku 46, 131-137.
Wang Li. 1982. Tongyuan Zidian. Beijing: Shangwu.
Zhengzhang, Shangfang. 1995. Shanggu Hanyu Shengmu Xitong [the Old Chinese system of initials]. ms.