@graham Hmm, from what I have seen in books and elsewhere while nasal helms where indeed the popular helms of the Viking Age (later Dark Ages) I am pretty sure the Spangenhelms as they are can cover that timeframe as well for alot of Europeans (like I have Later Dark Age sets with these and have heard no accuracy complaints about those particular heads so they work at least in a handwave way, though I get the feeling they where used through the Early Crusades in real history). Barring that you can always either swap them out or use a bit of green stuff for the nasal guards, frankly I feel proper nasal guard helms should'be for the "named barbarian tribe that actually had them" sets.
As to lamellar helms, again I think that should be in "named barbarian tribe that actually had them" and/or put in the Roman AB that would be Eastern Rome.
That aside the main focus of WA's plastics for both Blood Oaths and thier Roman line really is more for the late "decline" of Roman to the rise of Charlemagne as opposed to the "High Viking Age to Normans", so they only really need to add helmets for that if they going to do headswaps and weapons.
Likewise, no I would say its actually too easy to cover that whole dangnabbit timeframe and possibly a little earler with one box, at least as far as most unarmored Northern European warriors go since they did not leave a whole lot to go on and the Romans and others who did write at the time kinda of put them into one box themselves😆.
Honestly I have seen folks use Germinic Tribesmen and anceint celts in thier Viking hords with little or no modification with appluse. Plus all of Victrix's dark age warrior offerings which I think were based on heavy research seem to all shop from the same pre Norman Conquest Hot Topic to the point where its kinda of boring and you wonder why Victrix bothered,(With the Victrix sets its like every piece of armor and clothing that random self proclaimed experts claim was unique to the Vikings is in fact just how normal European warriors everywhere dressed and equipped themselves through that timeframe since the fall of Rome🤣). So yeah I am pretty sure a 1 box AB works here.
Also re-look at the cost, for this AB it is $34.99 (roughly $35) at pre-produaction order with a planned finished price of $39.95 (roughly $40). Last I checked (which was as of this post) 25 British Pounds is exactly 32.66 USD, and depending on how things go in the next couple of months the value gap between the pound and dollar could lessen even more