you can always use Perseus when in doubt:
δεδαῶτε is the dual pf act participle nom/acc/voc. δεδαώς is the nom. sg. masc. participle form
(the root in the pf. is δαε- according to Smyth and in §309a. he gives a list of similar verbs with contracted participles of the 2nd pf.)
so I guess that explains the omega and the accent position. http://www.perseus.tufts.edu/hopper/mor ... e&la=greek
I couldn't find καινύτω in Perseus but under καίνυμι, LSJ has:
Act. only in imper. καινύτω, μή σ' ἀπάτη φρένα κ. Emp.23.9
it is the 3rd. sg. form and it follows the imperative pattern of -vu-μι verbs.