A standard bearer always has the same profile as the other rank and file models in his unit. Similarly, we also treat him as being equipped with the same weapons and armour as other models, although the model itself might not be armed the same way.
In reality, the standard bearer model will probably lack a shield, or will have exchanged a weighty lance for a sword. Such is to be expected – a standard is a terribly weighty thing, and standard bearers often shed other burdens in order to keep the flag flying. The standard's the important thing after all – we can well imagine the bearer setting aside other trivial burdens to allow the mighty flag to be held aloft.
We furthermore take this deficiency in wargear to be compensated for by the sheer fighting skills and tenacity of the warrior in question. Only the toughest soldier in a unit will be given the honour of carrying the standard, and therefore we assume the standard bearer fights as if he has the same equipment as his fellows (which makes things far easier to keep track of!).