does attaching an enchantment Aura to a colorless creature make the creature the color of the Aura? My opponent has a card with protection from all colors and I have a Brass Squire with Armored Ascension attached to it.
No, your creature will still be colorless. An Aura would only change the color if specifically said so, such as Sinister Strength. This means that your opponent's creature is not protected from your Brass Squire.