The Parish, and date, listed in the Wills index refers to where the Court was sitting at the time of probate.
This is usually the same as the Parish of residence at the time of death but need not be so.
In the same way, the date in the index may be a year later than death - very occasionally much later.

The Will index tells you where to find the Will, not the death.

Bra = Braddan
Onc = Onchan
Dgs = Douglals

The Court did not necessarily sit in each Parish in each year. A resident of Douglas could have a Will probated in any of the above parishes.