The dedication is drawn from The Divine Comedy, the 14th century epic poem by Dante. The Divine Comedy is divided into three parts — Inferno, Purgatorio, and Paradiso — describing Dante's journey through Hell, Purgatory, and finally Paradise. Eliot returns to this poem throughout The Waste Land.
Here, the dedication translates as “the better craftsman,” a reference to Canto 26 of the Purgatorio. Dante refers to the poet Arnault Daniel, but Eliot passes the compliment on to Pound, who helped edit The Waste Land. Eliot returns to the same canto in line 428.
More context, from the Cotter translation of the Purgatorio:
This information is based on a footnote from North (2001). For more on Pound's contributions, see the annotated manuscript of The Waste Land in Eliot (1971).