Don't let this report to be abandoned!
Looks like, looking in UOFiddler, a new item called "Winged Helmet" is created (NOT "Winged Helm" cabbage-like which is the one the Helm of Swiftness used to appear).
Now, this can be fixed in 2 ways. I'm going to post both. One patch is much RunUO-friendly, the other one much Demise-friendly IMHO.
helmofswiftness_SVN1083_serialize.patch is the one Demise-Friendly. It basically just changes the ItemID and does the same in serialize/deserialize.
Pros: no pre-patch cabbage-like Helm of Swiftness; few code.
Cons: no particular cons. Code-wise speaking, it is still the Winged Helm, but with different graphics.
helmofswiftness_SVN1083_wingedhelmet.patch instead does what I wanted time ago to do with the Reedemer and the Paladin Sword: it
ADDS a new item called "Winged Helmet" and lets the Helm of Swiftness to inherit from that.
Pros: There is a new toy in RunUO (Winged Helmet), although the probability to see it in Demise is near to 0%
Cons: will leave pre-patch cabbage-like artifacts (I dunno if you can "on the fly" change inheritation, I believe no)
I leave the choice to the forum