He also appears to be unarmed with no armor. Hardly someone I'd give the army battle standard.
Just like later, in 4th/5th ed the Battle Standard bearer could be given whatever armor, or could go unarmored. (Not saying unarmored was or is a common choice.)
90's Empire figures often had varied armor compared to their game stats. No full plate yet, and the distinction between light and heavy armor could be minimal. Probably more a sculptor's choice than dictated by the army list.
And you might argue that historically, various styles of surcoats etc. were worn over the armor in certain periods. It would be very fitting for a herald/BSB to show the colors instead of the metal armor. Even the 'landsknecht uniform' was in some occasions worn atop of the armor.
The model was sculpted by Adam Perry and released in 1992, and was also available in the "Heroes of the Empire" box, together with Ludwig Schwarzhelm, the Supreme Patriarch/Thyrus Gorman and the Captain of the Reiksguard/Kurt Helborg. All the others got rules of their own at some point, but apparently not the Herald.
Well, he is also the one without a proper name, so not of 'hero material'.
The 4th ed book, p. 82, reads "Imperial Herald with Battle Standard", so clearly the figurine was meant to be used for a Battle Standard bearer. Perhaps the figurine has the horn just to elevate and differentiate it from other standard bearers?
The fluff in the 90's usually included the Emperor whose standard, according to the rules, is carried by his champion (Ludwig Schwarzhelm). There isn't much talk of imperial battle standard bearers other than Ludwig. The Herald gives you a figurine to use when you don't want to have Ludwig as your BSB. In that sense the figurine makes sense also for strict game purposes.
-Z