Glad you liked the ideas!
I think that if there were to be any fantasy upgrade sprue to do first, it would probably best start with some Elf and Hobgoblin heads: not a very exciting foundation, I think, but hobgoblins in fancy samurai-style helmets seem to be a popular request among fantasy tabletop gamers for whatever reason, and either type of head can instantly upgrade pretty much any Wargames Atlantic historical Dark Ages kit to generic fantasy pretty much as-is! (The Irish and Goths would make fine Tolkien-style elves, given the option of some typical pointy-eared and long-haired efl heads, while the Franks and Late Romans would make fine fantasy hobgoblins, given the option of those inevitable Samurai-style hobgoblin heads.)
It's just a question of what to add to that base in the form of weapon arms and accessories - if the first Death Fields sprue (a half-sprue size) is used as a template - which seems fair enough to me - it looks like there's room for two sets of 5 or 6 heads (that is, enough room for a small selection of Elf and Hobgoblin heads), and two, maybe three sets of different paired arm/weapon options for five or six figures. That would give us one or two fantasy weapon options suitable for arming a single sprue from a historical kit, which probably already includes spears/polearms, swords/melee weapons, and bows or slings.
Most Dark Ages historical kits will include broadswords or shortswords for the melee option with the occasional throwing axe or knife (or the great little warclubs from the WGA Dark Age Irish kit), so I'm thinking the fantasy weapon options for a first sprue might best include some some of the popular but uncommon fantasy melee weapon options: maces and morningstars, battle axes, scimitars, warhammers, flails, and spiked clubs.... Given the elf and hobgoblin-samurai theme, though, perhaps something better suited for elves and hobgoblins might work better: scimitars and rapiers, perhaps?
That sprue, combined with any of Wargames Atlantic's excellent Dark Ageshistorical kits, would pretty easily cover a lot of popular fantasy ground, without the need for a dedicated elf or hobgoblin box.
So, Fantasy Sprue #1:
- Elf Ranger Heads (5-6x),
- Elf Ranger rapiers (5-6x)
- Hobgoblin Samurai Heads (5-6x),
- Hobgoblin scimitar/katana arm pairs (5-6x),
- Fantasy accessories as remaining room allows (scabbards, belt pouches, etc.)
Then, in no particular order:
For a second sprue, there's at least one thread in the forums suggesting a fantasy monster head sprue for various weird fantasy creatures, which sounds to me like it would be great for converting Dark Ages figures into cat-people, wolf-men, ape-men, demons, pig-faced orcs, squid-faced sanity-eaters, and so on. Include a few more melee weapon options left over from the Hobgoblin/Elf sprue (clubs, flails, etc.), and you're probably set. This might be best done as a fairly random beast-man sprue, though something focused on one or two factions, similarly to the Elf/Hobgoblin suggestion, might prove more popular (say, enough bits to convert five or six figures into either cat-people or devil-born....)
A third fantasy sprue might be dedicated to fantasy spellcaster gear: staves, wands, grimoires, scrolls, potions, familiars, and the like, as well as the usual array of beardy wizard heads in pointy hats, gaunt necromancer heads, skeletal/mummified lich heads, cleric holy symbols, charms and amulets, and so on... unlike warrior armies, spellcasters tend to be an individualistic lot, so there's room for a lot of variety with little or no duplication here. If you keep enough of the sleeves and hats generic, this kit can upgrade Victorain up to modern figures into (say) gothic/pulp horror cultists and investigators, or modern urban fantasy characters, or sci-fi psychers, or post-apocalyptic veterans of a psychic war, or whatever.
More than one person has suggested an undead/gothic horror conversion sprue for turning historical figures into zombies, ghouls, and other living dead. I think that sounds like a fun idea, and to me, the greater the variety of undead and ghouls that can be included in such a sprue (vampires, mummies, maniacs, ghosts, bogeymen, etc.) Weapons options can be kept relatively simple here - given the subject matter, I think a few things like a meat cleaver, butcher knife, claw-hammer, sickle, crude club, femur bone, and the like work well, as would bare claws, but I'd rather see a good variety of monster head optons than monster weapons. And, frankly, I rather see a full-on generic gothic horror set than just a sprue, with gaunt, twisted bodies dressed in rags to match the heads and simple weapons, but that seems to be a heavily "Your Mileage May Vary" situation, compared to a dedicated zombie kit (for example).
And naturally, I'd enjoy that upgrade sprue of those "Grimdark" Solomon Kane style bits, for sure - some of those great wide-brimmed,conical hats, the blackpowder guns and swords (with off-handed pistol and dagger options, naturally, staves, tomes, amulets and holy symbols, capes.... I'm dying to see the gaming industry shift gears for fantasy gaming settings out of pale and slavish imitations of Tolkien, and this would certainly be one alternative I'd really enjoy seeing! This add-on sprue would just need a suitable historical kit to source the bodies and more generic weapons from. Appropriate additions to Wargames Atlantic's new Reniassance line would certainly do nicely here. I'd be fine using @Brian Van De Walker 's pitch for generic cuirass-trousers-and-boots militia as a foundation here. I suppose this add-on sprue would work well with the conquistadors, too, come to think of it. I think it's a question of how niche this set might be, though: I think I can see a lot more people going for generic fantasy elves and hobgoblins, but I'd hope they'd be willing to give a different flavor of fantasy enough of a chance to make this Solomon Kane-style set economically viable!