I recently got hold of a copy of EMH M’Kerlie’s (1916) Pilgrim Spots in Galloway. In the chapter on ‘Kirkpatrick Durham and Kirkpatrick-Irongray’ it mentions Angel Well (NX 8733 7770) and Angel Chapel (NX 8739 7764). Neither of these names are recorded on the 1st edition or subsequent Ordnance Survey maps (though they do get a mention in the Name Books). Both the well and chapel have CANMORE entries but as the the original sources aren’t that easy to access, I’ve copied them below.
‘Angel’ place-names are, unsurprisingly, not particularly common. The Saints in Scottish Place-Names database records eight: Cnoc nan Aingeal (North Uist); Angels’ Hill (Lochalsh); Tom Aingil (Kilmonivaig); Cnoc Aingil (Lismore); ?Tom nan Ainil (Balquhidder); Cnoc an Aingil (Glassary); Cnoc Aingil (Kildalton & Oa); Angel Hill (Kirkcudbright). In addition to these, the Ordnance Survey Name Books include Angels Burn (Aboyne & Glentanar: OS1/1/4/62, OS1/1/9/89).
All but two of these names are Gaelic and only one (Angels Burn) isn’t a hill name. In this context, Angel Well and Angel Chapel are notable not just for adding to the corpus of Scottish angel place-names but for being Scots/English names and for referring to features that aren’t hills.
E. Marianne H. M’Kerlie (1916) Pilgrim Spots in Galloway, London: Sands & Co., pp. 211-213
In the absence of all other tradition, who so  fitly as St Patrick may be connected with what was once the Angel Chapel and the Angel Well at Barnsoul? — he who lived in such familiar converse with his angel guardian.
Now hardly known, unmarked on any map, the spot is chiefly regarded as an ancient fort; an, were it not for the sweet-sounding title of the Angle Chapel, the interest would be chiefly for the archæologist or the lover of beautiful scenery. Bu the title is a magnet; and the road, at least from Dumfries, most beautiful all the way to the romantic “Routin Brig,” under which the old Water of Cluden tumbles over the rocks, in miniature cascades, to join the Cluden water; then the wild hills, of which one is Skeoch, as seen from Barnsoul, lying a little to the south.
On arriving here, the usual inquiries were necessary. The farmer’s wife knew nothing of the Angel Chapel and Well, but a bright little girl did, and her father knew more. He was the fetched, and conducted me tot he site. This is in a big, rich, sloping field, and on the June day of my visit it was a veritable carpet of buttercups and daisies. Six or eight Ayrshire calved tried hard to follow us into it; and the man, remarking on its richness, said that he had heard that it was blessed by the monks long ago. Then he pointed to a mound, with some old thorns on either side, and on going up into the grassy enclosure, it presented the form  of a horse-shoe, and this is the site of the Angel Chapel. A little below is a circle of rounded stones, — the basin of a spring. This was the Angel Well, whose waters have been diverted for the purpose of draining the land, and which now find their outlet in an adjoining burn.
F. Coles (1893) ‘The Motes, Forts, and Doons in the East and West Divisions of the Stewartry of Kirkcudbright’, Proceedings of the Society of Antiquaries of Scotland, 27, pp. 92-182 [at p.112, n.1]<http://journals.socantscot.org/index.php/psas/article/view/6512>
Half a mile N.E., and much lower down, on Barnsoul, there is marked on the O.M. the site of a chapel. From Mr Welsh, proprietor of Macnaughton, I learned that there were records extant in his family bearing on this point. So far as may be judged by actual survey of the remains as they now are, the notion of an ecclesiastical or of any other rectangular walled building, indeed, would be the very last to be suggested. The site is a horseshoe-shaped flattish space, within what certainly seems to be nothing more or less than a rather unusually broad rampart of earth and stone — in parts quite 20 feet wide — and having interior diameters of 75 x 75 feet. wing, however, to ravages made by ploughing and sundry unequal parts which incline to the angular, and help to render this curious site incompletely curvilinear, I do not feel justified in assigning it a place in my survey. Mr Welsh avers that it was known as The Angel Chapel, and a spring of water in the hollow to the N. goes by the name of The Angel Well to this day.
Ordnance Survey Name Book: Chapel (site of) OS1/20/64/12 (1848)
The site of a chapel on the f[arm] of Drumcloyor house of Barnsoul, no remains of the […] can now be traced out, althoug[h] the spot is surrounded by an [em]bankment of earth and stones […] covered with grass and thorn but W. Alex. Welsh & his brother Jam[es] Weslh of Macnaughton whose ancestors have been residents in the locality for more than a c[en]tuary past, say that they have heard it as a tradition from their father & from others; that a chapel existed here at some remote peri[od.] The name Chapel Rig which applies to the eminence would in a deg[ree] confirm this tradition also sometime ago, a well near this place which [is] now closed up was called Angel Well. & which is evident had some connection with the chapel.