Usage: 2 forms in 2 verses
Form Translated As     In Verse(s)
αξιόπιστοσ worthy of trust LXX.Prov.28.20
αξιοπιστότερα More worthy of trust LXX.Prov.27.6

Liddell-Scott-Jones

ἀξιόπιστος (axiopistos) worthy of trust G:A--C

ἀξιόπιστος-πιστος, ον,

trustworthy, [Refs 5th c.BC+]sufficient for.., [Refs 1st c.AD+]: comparative, [Refs 1st c.BC+]

__2 of evidence, trustworthy, [Refs 4th c.BC+]. adverb -τως, . συνῶπται[Refs]
__3 in bad sense, plausible, in adverb -τως[Refs 4th c.BC+]