The headword is perhaps (though not necessarily) extracted from the first quotation given.
[1] Polybius fr. 12 Büttner-Wobst. Adopting an emendation due to Schweighäuser, Büttner-Wobst (p. 515) reads kaqi=kto (third person singular, pluperfect indicative middle-passive of the verb kaqikne/omai, I come down to, reach, touch) for the Suda's kaqh=sto (third person singular, pluperfect indicative middle of the verb ka/qhmai, I sit, sit still, remain). Schweighäuser's revision is most likely motivated by the evident tension between the core meanings of the verb kaqh=sto, which evoke a complacency on the part of the subject, and the preceding participial phrases, which describe his vigorously staving off a number of personal (political and military?) threats as well as his perseverance against a host of medical travails. To accept the emendation, take the proposed verb in the passive voice, and render the participles circumstantially into English thus suggests the interpretation: ... but he had been affected, both while pushing these things aside and laboring through his illnesses, and he continued prosperous the whole time.
[2] Polybius fr. 13 Büttner-Wobst. Büttner-Wobst follows the Suda, but notes (ibid.) that here Schweighäuser suggested that e)pe/sthsan (third person plural, aorist indicative active of the verb e)fi/shmi, I set, set up, set over, stop, halt, check) replace a)pe/sthsan (they held back).