Something that I have been saying since playing D&D in the early 80s is that a DM must take his or her self 'out of the loop.' That is to say, the less immediate influence you have over your own world, the better. That influence should be moved towards the rules, towards the dice and towards the setting of your world. Specifically, how should things be if the setting of your world, and not your own feelings about it, makes the final ruling?
This happened to me last night, while making a determination about a player's horse, and I felt I had to write about it.
But here was the real kicker. Wikipedia, it should be noted, says this about the breed:
"Between the 16th to 19th centuries, Naples and the surrounding regions were known for their high-quality Neapolitan horses. The best horses were bred by nobles for transportation and cavalry. At the beginning of this time period, the horses were likely small, coarse and heavy, suitable for carrying heavily-armored warriors. However, as elsewhere, the use of firearms brought on the desire for a more attractive, agile horse."
And of course, because I don't have fire arms, I had to accept - quite happily, I might add, because as I said I love when my world pushes me out of the way - that the player character's free horse - one which the player would have known since it was foaled - was a heavy warhorse, and not a light one.
The player was understandably happy about this.