1. Random historical fact pop-ups (optional) when dead. They should be about the war or life in general during this time period.
2. More maps focusing on naval battles, including large ships. Possibly even water-only maps.
3. A damage-based score system, similar to the old Half-Life 1&2 mod Battlegrounds. Total damage is displayed instead of kills.
4. Sappers gaining score from damage dealt to structures they built, if the above system is implemented.
5. Musicians getting the same. Perhaps a percentage of damage friends deal while under musician buff.
6. Real-time officer buffs. When an officer says "retreat," we get a 5 second speed buff. When he says present arms, we get an accuracy buff. When he says "Hold this position" we get a minor defense buff. Game should automatically determine who has the highest rank for this to work, and it should be only one person per team.
7. Half-Life system commands. Timeleft, Nextmap, Votekick, Voteban.
This is an amazing game and I think some or all of these things can make it even better.