What happened to the Hussar philosophy for Weir? If he really wanted to help Custer he would have charged with bugles blaring and men cheering. That may have been enough to give Indians pause in thinking about more soldiers attacking. They may have fallen back. Instead they saw soldiers sitting around doing nothing and gave the warriors the confidence to charge without thought of numbers or danger.
Weir was bold but not suicidal. 40 men were not going to break thru 500+ warriors between his position and Calhoun Hill. But I think your suggested course of action has merit had it been attempted by the remaining 4 or 5 Companies of Cavalry that were otherwise unoccupied at the time.
"The more I see of movement here (Little Big Horn Battlefield), the more I have admiration for Custer, and I am satisfied his like will not be found very soon again.”
~ Gen. Nelson Miles, Commanding General of the Army ------
"With our cherished ones deliverance within our grasp we waited breathless two hours, for the order that never came."