I think the point is more that the war itself is far too short, rather than that it needs another timer. I'll write a bit more on this someday, but in a nutshell: Progressing too fast, while not having enough war-related content. I think gatekeeping progression like mansion upgrades and perhaps the farm would be a better choice. I.e. giving people a reason for wanting to complete it rather than forcing a timer.
For example: Ore could cost more while the mine is not in your possession, or not be available at all. Classes being gatekept behind progression in the story, perhaps in the form of teachers that aren't available.
Minor annoyances that don't force people to progress if they don't want to but also don't let them get strong enough to cheese the game.
Paladin for example should imho require you to have Knight + Templar and Holy attacks should be restricted to Priest, Bishop, and Paladins in particular. Other classes should have similar flavor. I have for example no real reason to pick Knight over Paladin, so that would give Knight a better use. Those classes in turn could be kept behind story related content, or sidequests, like the Priest class is.
Another thing regarding classes is that there should be a maximum (not counting Master, and so on though. the master is already pretty weak compared to the Servants. )
And last but most importantly: Available quest rewards. I literally got a full, average levelled, Draconic Lance for slaying an Ogre, which is really easy even without a healer.