Hi,
There are only 4 Joseph Davies in Abercarn 1901 assuming they were living there then.  Out of these 1 is born about 1857 so I think can be discounted.  This leaves the following:
Joseph Davies 15 Bedwellty, Monmouthshire, Wales Son  
Joseph E Davies 11 Newbridge, Monmouthshire, Wales Son  
Joseph J Davies 12 Mynyddyslwyn, Monmouthshire, Wales Son  
As no middle name was used when he married my favourite would be Joseph Davies age 15 as he is also the correct age.  His father is also called John so here are the full details:
10 Jones Terrace, Abercarn, Monmouthshire   RG13/4968 129 29 
John Davies 54 Langoteg, Breconshire, Head Coal Hewer
Ann Davies 44 Bedwellty, Monmouthshire, Wife  
David J Davies 16 Bedwellty, Monmouthshire, Son Coal Hewer
Joseph Davies 15 Bedwellty, Monmouthshire, Son Coal Hewer
Seth Davies 11 Cwm Carn, Monmouthshire, Son      
Ann Davies 9 Cwm Carn, Monmouthshire, Daughter  
Thomas Davies 7 Cwm Carn, Monmouthshire, Son  
Joseph E Davies also has a father called John so I will give the details just in case.
RG13/4967 71 39 52 Greenfield, Abercarn, Monmouthshire    
John Davies 43 Tredegar, Monmouthshire, Head  Colliery ??man below ground
Annie Davies 35 Tillington, Herefordshire, England Wife  
Margaret Davies 13 Newbridge, Monmouthshire, Daughter  
Joseph E Davies 11 Newbridge, Monmouthshire, Son  
David J Davies 10 Newbridge, Monmouthshire, Son  
Winifred R Davies 6 Newbridge, Monmouthshire, Daughter  
Wm E Davies 2 Newbridge, Monmouthshire, Son  
John Davies 1 Newbridge, Monmouthshire, Son  
I would also be a little wary of taking their ages on marriage as correct.  A quick check for Alice Trenery born in Cornwall brings up only one possibility age 9 in 1901.  Of course she might not be the right one but I have numerous examples in my own tree of people lying about their age on marriage. 
Are there any Davies witnesses to the marriage?  Just wondering if they match anyone.
Good luck with your search
Debbie  
