Unfortunately I do not believe that this is found within the DateTime function. If you have a look at the FDateTime function here:
It does not include day of the week. What documentation were you looking at that indicates it should be included, I’d like to be able to see which is accurate so we can update the documentation appropriately.
It appears that the GetDayofWeek function is not available in blueprints for a DateTime variable. All the other functions seem to be there. Is this a bug in 4.9 or a known issue? The documentation seems to indicate it should be there.
More specifically, I have created my own DateTime variable and filled it with a default value. I manipulate it by adding seconds to the date and that is working, but I see no way in blueprints to get the day of week value from the variable.