Yep might be a bit too far to put together 91 and 94, but actually the rule texts were identical except for a few minor changes as I recall. The xp-table (to buy skills) was muddled up in 94. Simplified perhaps, but lost a lot in long term playability. There was also some changes in how you rolled perfect and fumble I think. Then of course there was a world description in 94 (Chronopia, which was awesome), and some new races for PC:s, but it was nothing mentioned of Chronopia in the other parts of the 94 book, just copy-paste.
Was not Gigant mostly some extra rules for Expert? About building castles and having armies? There was also DoD Ivanhoe as an expansion in the same league.
There were lots of other expansions, some of which made DoD to a whole different game rules-wise as I recall, like Krigarens Handbok to 91.
Samurai was its own game, so could be an edition… But it really felt like another game. It had no elves, ducks, halflings, dwarves or anything. It had a demon called something from a sushi menu though, Yakitoro?
Yes Gigant is most famous for adding castles and such but there are also a lot of rules for making characters incl professions, skills, hero abilities, magic and so on. I know it´s there but do not really remember how similar these rules were to the ones in Expert.