Poetry

[heslopian]

The birth of poetry,a bodily function,
the building pressure of a sneeze

as birthing a child, a slow and painful An awkward transition from sneezing to birthing. It's so abrupt that one could almost say you're mixing metaphors: a sneeze is sudden, while birthing, to quote you, is "slow and painful".
process of anticipation Another awkward transition. Is the birthing underway or are we anticipating it?

or the dreamy, enticing excitement of a love lust tryst I think "love lust" might be more effective if you put a slash between them.
exploding into orgasm, release beyond all reason I think I see the problem with your metaphors; they follow each other at such a fast pace that they're not clearly defined and so melt together, making them seem clumsy. Maybe you could remedy this by separating your stanzas a bit more, like so:

"The birth of poetry is a bodily function,
the building pressure of a sneeze.

It's also like birthing a child, slow and painful,
preceded by a process of anticipation.

Or is it the dreamy, enticing excitement of a love/lust tryst
which explodes into orgasm, release beyond all reason?"

That's just a crude example, of course.

in the final thrust of a jouster's lance
that bleeds out victory on the ground I like the phrase "bleeds out victory".

The poet, that wretched soul
destined for greatness
or for death These three lines feel redundant; everyone's destined for greatness and/or death.
imbibes the painful truth
and gives us its beautiful device Great last two lines; sharp and poetic. I like the use of "imbibes", which makes "the painful truth" seem like a bitter medicine, while "beautiful device" is a neat semi-metaphor for poems.

You have some good stuff here, it just needs a bit of tidying up. Take a broom to the first three or four verses and you'll have a very effective poem. Critique is, of course, JMHO. Thanks for the read