Must not strive (ou dei machesthai). Rather, “it is not necessary for him to fight” (in such verbal quibbles). The negative ou goes with dei, not with the infinitive machesthai.
Gentle (ēpion). Old word (from epos, speech), affable, mild, in N.T. only here (and 1Th 2:7 in some MSS.; W. H. have nēpios).
Teachable (didaktikon). See note on 1Ti 3:2.
Forbearing (anexikakon). Late compound (from future of anechō, anexō, and kakon, putting up with evil). Here only in N.T.