Oblique type and italic type are different font styles. Oblique type is always slanted to the right (at least according to Wikipedia). To the best of my knowledge, nowadays almost all italic types in widespread use—and suited for the typographical requirements of written English—are also slanted to the right.
Is there a verb form of ‘oblique’?
According to the Merriam-Webster entry, ‘italicize’ may mean either of “print in italics”, “underscore with a single line” and “emphasize”. Cambridge Dictionary states only the single meaning “to print or write something in italics”. I find Cambridge Dictionary much more reasonable in this case. But in cases where one simply wants to say that a slanted font style indicates emphasis: if one meaning of ‘italicize’ is synonymous with ‘emphasize’, then—since conventionally oblique type may be used for emphasis—‘italicize’ may perhaps be used as a substitute for the possibly non-existing verb form of ‘oblique’?