Alright this thread got out control.
I agree with Rogojel's post #19 and meanjoe's generalization in # 26.
I did the math and their approaches give the same result as my proposed method of stratifying on one of the variables and looking at the ratio of the two ORs.
Their appoach, calculate the expected OR via the product of the OR of W and OR of X6 = 18.86, then multiply that by 0.539, which equals actual OR in the model for outcome given both condtions present (i.e., odds of both present over odds of neither present). This value is 10.16. Which we can see is a negative multiplicative interaction.
The method I was proposing was to calculate the OR of W present versus not present in patients with X6 present, divided by, the OR of W present versus not present in patient with out x6 present.
Thus the OR of W*X6 = observed/expected, and since it is < 1, the observed was lower than expected if the two covariates were truly independent. And given my approach it means the percent lower the OR was when the second variable was present versus not present. Big picture the cross product term in the model represents the deviation of the two lines from being parallel (lines are the plotted log odds based on stratifying on one of the two covariates of interest).
Thanks everybody for bearing with me while I also tried to wrap my head around this!!