(Addresses Self-Harm/Abuse) She'll One Day Forge Beauty - Edit 1

[Leanne]

Hello there Mr Weiner sir!  You have a quite confrontational poem here, and it's loaded with emotion so it's not an easy one to critique.  Please bear in mind these are criticisms always of the poem, not the poet or the subject.

Six-year-old girls shouldn't
need to place their sadness
between their toes 
and the business end of a hammer, -- this is a strong opening, immediately setting the scene in pain and conflict.  We assume, because she is six, that this is someone else inflicting pain on her at this point.  I am not convinced about "business end", as it seems a little too light and idiomatic.

striking at anguish left -- still thinking about this line break -- i.e. should "left" be left here? Also, is "left" the best choice of words?  
red hot by bourbon blows and -- this is the point at which I change my mind about who is weilding the hammer.  It seems as though despite being six, the girl has already suffered sufficient anguish to feel that she must inflict pain on herself.  This is when the heart breaks.
neglect. Their little digits
lack the temperment of anvils, -- *temperament or *temper, if it has been tempered

and while the blacksmith 
keeps a bucket of oil at hand -- this is a good analogy but I feel like you're missing a chance to put salt water and brittleness in here somewhere
to harden his work,
muffled cries do little 

to quench the misery of one
with such limited understanding. -- this line is a bit on the tell-y side
I cannot comprehend the mind -- I'm not convinced that bringing in the "I" works.  It shifts the tone quite a long way out of the mood you've worked so hard to establish and becomes a bit preachy.
of a girl so tortured,

or how she could learn
to hang up her hammer 
and forge a life for herself 
so beautiful as yours. -- personally I'd drop this line, or change it so that it doesn't make the poem so specific to just one person (even if it is -- after all, she will recognise herself anyway).