Can old vintage quartz crystals handle more power?
Power handling ability of a crystal seems to be directly related to size. The dissipation is related to the ESR though. 

Small SMT crystals might be 100uW-500uW max. HC-49 crystals can handle around 1mW. Some older crystals can handle as much as 10mW. 

See this 1972 crystal catalog. 

Here is a chart from that document showing the typical drive power vs plate voltage: 



Overdriving a crystal can lead to premature aging and even failure.