Additional rewards followed, including the renewal of his exchequer auditorship (though he may have continued to enjoy it since his first appointment) and ten pounds to his pension. The only biographical evidence of his closing years is his signature as a witness to sundry deeds in the "Register of Aberdeen" as late as 1392. According to the obit-book of Aberdeen Cathedral, he died on March 13, 1395. The state records show that his life-pension was not paid after that date.
Considerable controversy has arisen regarding Barbour's literary work. If he is the author of the five or six long poems which have been ascribed to him by different writers, he adds to his importance as the father of Scots poetry the reputation of being one of the most voluminous writers in Middle English, certainly the most voluminous of all Scots poets.
The Brus, in twenty books, is a narrative poem with a purpose partly historical, partly patriotic. It opens with a description of the state of Scotland at the death of Alexander III (1286) and concludes with the death of Douglas and the burial of the Bruce's heart (1332). The central episode is the battle of Bannockburn. Patriotic as the sentiment is, it is in more general terms than is found in later Scots literature. The king is a hero of the chivalric type common in contemporary romance; freedom is a "noble thing" to be sought and won at all costs; the opponents of such freedom are shown in the dark colours which history and poetic propriety require; but there is none of the complacency of the merely provincial habit of mind. The lines do not lack vigour; and there are passages of high merit, notably the oft-quoted section beginning "A! fredome is a noble thing."
Despite a number of errors of fact, notably the confusion of the three Bruces in the person of the hero, the poem is historically trustworthy as compared with contemporary verse-chronicle, and especially with the Wallace of the next century. No one has doubted Barbur's authorship of the Brus, but argument has been attempted to show that the text as we have it is an edited copy, perhaps by John Ramsay, a Perth scribe, who wrote out the two extant texts, preserved in the Advocates library, Edinburgh, and in the library of St John's College, Cambridge.
Yet another work was added to the list of Barbour's works by the discovery in the library of the University of Cambridge, by Henry Bradshaw, of a long Scots poem of over 33,000 lines, dealing with Legends of the Saints, as told in the Legenda A urea and other legendaries. The general likeness of this poem to Barbour's accepted work in verse-length, dialect and style, and the facts that the lives of English saints are excluded and those of St. Machar (the patron saint of Aberdeen) and St. Ninian are inserted, made the ascription plausible. Later criticism, though divided, has tended in the contrary direction, and has based its strongest negative judgment on the consideration of rhymes, assonance and vocabulary.
Attempts have been made to name Barbour as the author of the Buik of Alexander (a translation of the Roman d'Alexandre and associated pieces), as known in the unique edition, c. 1580, printed at the Edinburgh press of Alexander Arbuthnot.