Oh what a wonderful word, this vex! It's short, sweet, ends in an "x" (how very sexy) and sounds lovely in old-fashioned poetry. Vex means "to annoy or harass." It comes from Old English vexen, from Old French vexer, from Latin vexare ("disturb, agitate"). In the Old English vocabulary, it replaced the word grillen, "to annoy."
And to demonstrate the use of vex in a lovely Victorian poem, we have Thomas Baily Aldrich:
I vex me not with brooding on the years
That were ere I drew breath; why should I then
Distrust the darkness that may fall again
When life is done? Perchance in other spheres--
Dead planets--I once tasted mortal tears,
And walked as now among a throng of men,
Pondering things that lay beyond my ken,
Questioning death, and solacing my fears.
Offtimes indeed strange sense I have of this,
Vague memories that hold me with a spell,
Touches of unseen lips upon my brow,
Breathing some incommunicable bliss!
In years foregone, O soul, was all not well?
Still lovelier life awaits thee. Fear not thou!
The Lonely Alchemist