The Draco standard

[Renatus]

We have be wary of that indeed, which is why I don't support such perverse logic. But we still have to take into account that the possibility exists. If we exclude that possibility, we are forced to take each text literally.

Of course one has to be aware of the possibility but that is not to say that the possibility actually existed. The problem is that I am a lawyer and lawyers like evidence. In fact, we insist upon it. In the absence of evidence, a case cannot be made. So, cite me the evidence of dracones being used as wind direction finders and I will review my position. Until then, yes, we have to take our sources as we find them.

Eagles never had serpent tails, nor did a vexillum develop into a battle standard with a streaming tail. Neither do Celtic, Germanic, persian battle standards which arer solid objects without streamers.
No, can't follow you there, because if this was a logical development we would see many more battle standards with streamers or tails, and we don't, at least not in this period. The 'draco' therefore, in my opinion at least, is far more likely to have been originally something 'with a streaming tail' than something that aquired this in order to function better.

I think that you misunderstand me. I have not said that it is a logical development for battle standards to develop tails or streamers. I simply likened dracones to the types of standards that had that characteristic. If the eagle could fulfill its function without streamers, so be it (I bow to your superior knowledge of the form of Celtic, Germanic and Persian battle standards but the same applies). As to the effect of the draco in battle, consider Julian at Strasbourg (Amm. 16. 12. 39):

Quo agnito per purpureum signum draconis, summitati hastae longioris aptatum, velut senectutis pandentis exuvias . . .

'On recognising him by the purple ensign of a dragon, fitted to the top of a very long lance and spreading out like the slough of a serpent . . .' (Loeb translation)