Arwelfa means 'Arwel's place' or 'Arwel's house' and is thought to refer to the home of John Hughes the composer in Rhosllannerchrugog*.
*Residents of Rhosllannerchrugog are often referred to as 'Jackos'. The original settlers in the area were believed to be Jacobites, banished from Wrexham town centre.
By coincidence the same town is the birthplace of Caradog Roberts (Rachie) and Tom Jones (1898 - 1984) - the politician, not singer*
*He was Labour Member of Parliament for Merioneth from 1951 until his retirement in 1966. Subsequently, he was given a peerage as Baron Maelor of Rhosllannerchrugog.
rhos "moor"; llannerch "glade"; grugog "heathery" hence "Moor of the Heathery Glade".