Cf. also wəkul ‘confisus, fretus,’ təwkəlt ‘confisio, fiducia, spes’ (LLA 920).
PNWS *ykl ‘to be able’ may be related.
According to a broad consensus summarised in Kouwenberg 2010a, 454 and Kogan 2015, 101, Akk. takālu is a diachronically secondary verb going back to PS *wkl “to trust, to rely”. The same type of secondary root has been independently produced in Arabic and Aramaic. As reasonably argued by Kaufman 1974, 106, the high proliferation of *tkl in Aramaic (notably, in opposition to its modest presence in Arabic) may be due to Akkadian influence on Aramaic or even to a direct borrowing from Akkadian.