New I'm really worried it'll just be Fates/Awakening/Shadow Dragon characters, especially after the teaser. They had Raijinto and Siegfried, but no Ragnell or Sword of Seals? That doesn't seem right to me. I want to wreck armies as Black Knight, not as Tharja or some other random-but-popular-waifu character (Sorry EODM07).
I'm fine with more Fates if it isn't at the exclusion of other games, though I'm also biased if they did the same thing but with Awakening; I just liked everyone better in that game compared to fates.
But even Tharja being added to the exclusion of, say, Micaiah would just be off.
We probably shouldn't put so much significance to Fates/Awakening/Shadow Dragon, tbh. Like, Fates/Awakening are definitely a focus and Chrom is definitely taking center stage (He got his chance some other day!), part of those weapons is probably because they're the most recent FEs, due to the Marth-Era DS remakes after Ike's games came out.
HW only had 13 characters at release but that's EXTREMELY small for a Warriors game so I'd put that as an exception.
Weapon count in HW is equivalent to Characters in the typical Warriors game, so 20 weapons in vanilla before patches and DLC. This was actually a relatively good number for a first iteration given the other crossover DW games, such as Gundam Warriors and Pirate Warriors. PW2, for example, had 27 characters.
That HW ended up with (effectively) 42 weapons / movesets for the first game of a DW spin-off series is much larger than expected.
To put it in perspective, it took Pirate Warriors three games to get up to it's current 37 characters, and One Piece really isn't a series wanting for memorable characters with good moveset potential.
But yeah, we should still expect to see a good amount of characters for a number of reasons.