See generally Photius, Lexicon kappa1000 Theodoridis with the references there.
[1] LSJ s.v. korw/nh II.2, as in Homer, Iliad 4.111 (where, as again here, it appears in the accusative case): "and smoothing it all well, he set on it [the bow] a tip of gold". This definition appears in Hesychius, and the Etymologicum Magnum.
[2] LSJ s.v. korw/nh II.7, as in Posidippus cited in Athenaeus, Deipnosophists 10.414D (10.7 Kaibel): the "high point" or "crown" of a festival.
The entire gloss also appears in the Lexica Segueriana, but with the tip as an end of a piece of wood (cu/lou), rather than a bow in particular.