Hogweard

These all belong to a short text on the appropriate days to bloodlet. Note that in the third example, "dæg" is only dropped after it has already been used several times, although one could argue that date formats are perfectly obvious to read without the day, and "dæg" is not grammatically required - you can just use the ordinal number substantively; BUT, the vast majority of historical examples include "dæg" - it would be a grammatically fine ''stylistic'' innovation to drop the "dæg". This fully verifies the "se Xa dæg on MONTH" construction, which would be grammatical anyway, if not idiomatic.

And that's what I'd find most desirable, but ofc "on þone X dæg Xmonðes" is also perfectly fine". Because the definitive article doesn't tend to be included in article titles, I'd be comfortable to omit the leading "se" in article titles for dates. I would suggest e.g. "(X/10)a (dæg) Winterfylleðes" for article titles.