Frequency that quartz crystal can handle
Except at its resonant frequency, a quartz crystal will not significantly mechanically respond to an input frequency. Therefore it will not be damaged. Only at or very near its resonant frequency will the crystal vibration amplitude be significant.  If the input voltage is then too high, the crystal vibration amplitude could exceed its mechanical strength capability and it could then be damaged. The very high mechanical Q of the crystal prevents this from happening at frequencies off resonance.