Romans wore helmet crests to signify their title and position amongst their ranks. Their color typically signified their house (i.e. House of Julii was red) but only Roman Consorts could wear their house signet on campaign. Auxillaries could not bear any crests (not Roman citizens) and even Legionaries (Roman citizens) could only bear it if they had significant importance in rank, title or office and it had to bear the color of their Cohort Commander. So I am told at least....
Bold part is kind of what I was thinking, identification as a group, but not an individual.
Also found this, from the bronze age Scandinavia/Russia. This example specifically is from Denmark.
Ah, okay. I thought you meant *horns* as in animal horn like hollywood. The pictures look metal, rather than wood/steel. And it's really throwing me off, but I swear the lone horn on the left looks threaded at the bottom, as if it would be removable (such as for battle), and used during ceremonials (as Sir Ian said). I can't tell if it's threaded, or just ringed, but both seem very unusual if it would be expected to be a permanent fixture on the helmet.
I would not say that their armor skills were not advanced. Their helms were quite decorated, along with fittings on swords, etc.
Advanced in regards to heat treating, articulation, and complexity. They certainly had very decorative items, and some that were crazy intricate in detail. In my head, that's different from the core function of the armor. Sorry for the confusion.
Thanks for all the info and opinions on this subject!!!
Also the above picture of bronze age helms, we see toppers like this on the royal Danish helm when heraldry is "used" or better said recorded.
If I'm reverse engineering this correctly, it's from a collection of heraldry, Armorial del Gelre, which is 1370-1414:
http://en.wikipedia.org/wiki/Gelre_Armorial. No doubt helmet toppers / crests were in use at this point, and at least 100 or so years earlier - my knowledge is severely lacking in that period, and I had to google for the crest info on this one, but I hope that helps.