Correct @jadenusa. From a purist standpoint, I would call this a 2 1/2 feather. With what remnants of the 3rd feather are left, this would be considered a 2F by a
TPG for
this date. To my knowledge, the 27-s always had a remnant of the 3rd feather remaining, some less than others. Smaller the feather, bigger the premium/demand. On a date such as the 25-s, common in 2F with no trace of the 3rd feather, this would fall short as there are examples with
no trace of the 3rd feather.
The 26-d for example, tends to have a faint ghosting of where the 3rd feather was, but should not have an obvious raised portion like the 27-s (though this raised portion on the 27-d is still weakened).
I also have a 1918 2 1/2 feather, which has slightly more than my 27-s. I've imaged it and taken close ups for die state reference, but not a true 2 feather. Very cool nonetheless!
Curious what your 26-d looks like.