Family search " Beta" has now on line St David's abstract of Wills. Some years are missing, however a huge help in research.
https://www.familysearch.org/Click on Europe
This will take you to Historical Records Collection
Scroll to the bottom of the page to Wales
Click Wales Probate Abstracts or Browse images
Llandaff and St David's is shown 1773-1780
Once you click on which ever Diocese St David's start from 1564 - 1836 ( with some years missing)
If you look at the National Library of Wales probate records and find the date, place name etc. The abstracts can with time be found. The first three pages of the year are Introductions etc. After which are the names and place. after this " Just Brilliant" if you have hours to kill! - Gives a list of every person named in the wills for that year.
Beneficiaries, Tenants, Debtors, witnesses, executors etc.
Remember you have to take into account these extra pages eg, Will numbered 1 - may start on page 32.
Once you have done some searching, you will pick up approx where to start.
Happy Hunting.
Jane