Portrait of a corpse

Hello IamI, I'm Morrigan, and I'm here to review your poem.

To be honest, I'm not a huge fan of sonnets, but I think that the language here actually fits the form. It's a little antiquated, but if that's what you're going for, good for you.
It's giving me a very 1860s vibe, like right after the US Civil War ended.

There are a few things that popped out at me that you could change to benefit your poem. I'll start with the smaller items, and then we'll move on to the meter in your piece.

Is veiled now by black, your form by black clothes.
You slumber now in your black satin dress,

You use "black" three times in two lines. I'll get to how you can fit other words into the meter later, but using the same word in such close proximity doesn't give off an air of a polished poem. Even if this repetition was intentional, it really sticks out to the reader as being unimaginative. Try to find other words to describe "black!"

I understand that this poem is literally just a portrait of a corpse, and you really don't have to add any more content, but somehow, this is lacking. I don't feel anything for the woman in the poem. The only hint of what killed her is

Still your demise may think you a worthless
Bride,

but that could just be figurative language. I encourage you to give more life (haha) to this poem. Help the reader connect with the subject of the poem. Death is a universal experience, and I shouldn't feel so disconnected from it.

Onto the meter! Bear with me. It's a trip.

Judging from the fourteen lines with the last two lines separated, you've tried your hand at a Shakespearean Sonnet. Usually, these poems are broken into four stanzas. If you're having trouble with the YWS formatting, I understand. In the publishing center, you can single space a line by holding shift when you press enter. Then you can simply press enter when you want to divide a stanza!

You are bang on with the rhyme scheme. The only thing I have to say is that "trims" near the end of the poem is a little awkward. While you can say "trims," generally speaking if all the trim is on one garment, you would say "trim" even though there might be multiple places where trim is found. It still rhymes well enough with "limbs." Honestly, when it comes to rhymes, I prefer slant rhymes, or almost rhymes. They make for a fresher sounding poem. If you're interested in slant rhymes, here's a great rhyming dictionary for you!

Shakespeare mostly wrote his sonnets in iambic pentameter. While you don't have to do this, it really helps the feel of a structured poem. You don't have to follow the rules, but the rules exist for a reason.

An iamb is a group of two syllables that start with an unstressed syllable and end with a stressed syllable. One example of this would be the word "describe." Say it out loud. deSCRIBE. Say it the other way, too, just for good measure. It sounds awfully strange!

When I say iambic pentameter, I mean a line consisting of 5 iambs. Penta stands for five. Since each iamb is two syllables, that means that there are 10 syllables a line. You can get away with 9 sometimes, but only if you end on an unstressed syllable.

In some lines, I can see evidence that you have a good ear for natural meter.

And does your countenance such grave disgrace,

If not for "countenance," this line would be in iambic pentameter! Let's break it down. I'll capitalize the stressed syllables.
and DOES your COUNTenance such GRAVE disGRACE.
You might even argue that you could say countenance with emphasis on "-ance," but I personally still think that sounds weird.

I want to talk again about this line:

Is veiled now by black, your form by black clothes.

What you have now is
is VEILED now by BLACK, your FORM by BLACK CLOTHES.
You almost had it in the middle there, but if we reimagine the words you use, and take out a few "by's," you can rewrite it to be in iambic pentameter and use two different words to describe black.
This is what I came up with, but you can obviously change it if you don't like it.

Is veiled in black, your form in onyx robes.

Now the meter looks like this:
is VEILED in BLACK, your FORM in ONyx ROBES.

Try challenging yourself by going through your poem and reforming the meter! Just having to be creative with that can really help you find different vocabulary to describe what's happening. I hope that this review is helpful to you! If you have any questions, let me know! Best wishes, and keep writing!