There are a number of results for "Wier" when searched on the Cambrian Online index. The actiual articles are not however online, but are accessible via the Swansea Library or West Glam Archives.
https://www.swansea.gov.uk/cambrian?lang=enLooking at the info available in the indexed entries, there would appear to be more than one Weir family living in Swansea.
Looking for one around the time of the 1849 death, this Thomas Weir could in fact be Thomas John(e)s Weir who married Catherine Kynaston in Penally 9 Mar 1827. He was described on marriage certs of some of his children including 23 Dec 1862, Briton Ferry, of Charles Bridger Wier to as Thomasine Lowether as "Lieutenant in the army. On Charles's baptism at St Clears
22 Oct 1833 Thomas Johns Weir is decsribed as " Gentleman."
On son John Alexander Weir's marriage cert 3 Dec 1870 at Kenwyn Cornwall as "Luit 1st Foot "
He is at High st St Clears 1841 with wife and family Class: HO107; Piece: 1382; Book: 1; Civil Parish: St Clare; County: Carmarthenshire; Enumeration District: 1; Folio: 7; Page: 5; Line: 11; GSU roll: 464309
1861 Catherine Weir is widowed and living with children at 1 Grove Place, along with her sister Martha Kynaston Class: HO107; Piece: 2466; Folio: 274; Page: 56; GSU roll: 104215-104217
There are also trees for the above.