I don't think the Templars are supposed to be itimidating or impressive in appearance, as they had rules that every one was to be "poor" and they disallowed any decoration on weapons, armour or clothing. What scared the Templars' enemies were not their appearance, but their reputation for being highly skilled and fanatical fighters usually fighting to the last man.
I think it was Saladin (though it may have been some other) who said that a normal Frankish army could be overcome with similar or even fewer numbers of men. But a force of Templars often had to be outnumbered 4 or 5-1 and even then you should expect high casualties. Their reputation led the Templars' enemies to fear their appearance even if their appearance alone was not particularly intimidating or awe-inspiring.