I've been mulling it over for a little while and I think there's a lot of things that could be added to improve the game. So here's my two cents.

Expanded Leaderboards. More stats means more bragging rights, and bragging rights fuel competition. It can only be a good thing.
It would also be a nice thing to have prominent players on the leaderboards face off in a variety of game modes and stream it over twitch. A night of valor, decapitations and backhanded strategies.

Clan (sub faction) integration (maybe call it warband or something). It would be nice for players to group together with other players in a faction. Share spoils and exp and so on. In my opinion the clans should be kept small (up to about 10 players, give or take) to avoid the typical 3-6 Juggernaut clans that no other clan can hope to rival, and instead incentivize clans to seek stronger players from their own faction, rather than a lot of players from different factions. And of course there should be separate clan leaderboards.

1vs1 Tournament mode. It would be a great thing to have since the matchmaking in this game seems to have a hard time filling the empty places that players leave behind when they quit. If 8 or so players join a round-robin style tournament and duel each other, it would be nice for getting consecutive matches with different opponents. It would also be cool if you added a single-elimination tournament where players knock each other out, while eliminated players were able to spectate the rest of the tournament.
This format would also work great as a clan vs clan face-off thing.

Grand Melee. In the olden times grand melees were a common thing in tourneys. Basically a bigger brawl mode. 4vs4 should be easy to implement seeing as it's the same amount of players as in Dominion mode. But if it could be expanded to say... 8vs8, THAT could be one hectic slug-fest! As with the 1vs1 Tournament modes i mentioned above, this would also work great with a clan system backing it up.

And finally I think every player out there would appreciate a more robust matchmaking system. As I wrote above, the current matchmaking system seems to have trouble replacing players that leave, meaning after every match everyone quits and finds another game for the sake of expediency. This is annoying, and I hope you guys take another wack at it before release.

With all that off my chest I would like to thank the devs for a great time with For Honor so far, with more good times to come, no doubt!

Good night y'all.