The... what? ...between his... what?
The scepter shall not depart from Judah,
nor the ruler's staff from between his feet,
until he comes to whom it belongs;
and to him shall be the obedience of the peoples.
The Lectionary, based on the NAB, steps in it.
The scepter shall never depart from Judah,
or the mace from between his legs,
While tribute is brought to him,
and he receives the people’s homage
There is a "Freudian" aspect here that may make some people feel uncomfortable (and understandably so), but if we are able to set aside the distractions of concupiscence, we can recognize that this ancient symbolism emphasized the paternal and life-giving aspects of ruling authority...
...the authority of God our Father and of his Christ – the fulfillment of this prophecy – a fortiori.