Star Trek ground forces can engage enemy forces at a range of a kilometer or more based on tricorder readings alone. Assume they can fire a phaser once a second and Signs Aliens cover five meters s second that means the Starfleet Ending can fire 200 times before melee.
Now Phasers barely ever miss. It is known and they can fire off axis but we'll be generous and assume a 50% accuracy rate beyond 100 meters. And Phasers are always lethal unless plot induced stupidity determines otherwise. So that's ninety dead Aliens.
At sub 100 meters the Phaser will be on wide beam. This will wipe out an entire cones worth of enemies to the point it'll require the aliens to climb over the bodies of the dead, halving their speed let's say. Each wide beam will have to be drowned out by bodies so we'll be minimalist and say five aliens killed per wide beam blast and forty wide beam blasts used.
So another two hundred aliens killed.
Now we reach melee. I know what your thinking, melee? Signs Aliens can take a beating from a professional level baseball player with a baseball bat. STFU for a moment and realize this...
Your average Klingon is a warrior trained from birth and three times as strong as a Vulcan whose three times as strong as a healthy Human Male. So a Klingon is as strong as nine Humans. Butt a Bajoran (who may or may not of been suffering from the effects of pregnancy) defeated three armed Klingons in hand to hand combat. Now Bajorans, don't let the fight choreography fool you, are highly skilled martial artists. And Starfleet Ensigns have access to encyclopedic level of knowledge from holodeck training and Ensigns given combat roles naturally would pursue as much training as possible.
So halving the effectiveness of an Ensign to a Bajoran Officer seems reasonable. So instead of being equal to twenty seven Humans, nine Vulcans or three Klingons they're only equal to 1.5 Klingons
But these Klingons were armed and armored so we'll double that back to three Klingons. So each Ensign is worth... Rounding down.. roughly twenty Aliens in hand to hand combat because they are strong and durable.
So that's it right? Wrong.
Over penetration is a thing. And with how densely packed these aliens would be so we will increase the total dead from phaser shots alone by 20% which is low balling it IMHO.
So... 90 + 200 + 20 x 1.2 = 372 Aliens
But we're not done yet.
Worf remember made a personal forcefield against kinetic impacts in the Old West Holodeck Simulation. A Starfleet Ensign could build one way more effective out of late 20th century rural technology and is likely far more intellectually intelligent then a Klingon.
So actually the Ensign could likely fight until he died of thirst or exposure or exhaustion, which is a matter of days.
So actually it'd be 372 deaths per five minutes rated out to three eight hours workdays.
60÷5×24×372 = 107,136 Signs Aliens killed per Ensign.
Low estimate. Generously it'd be much higher.
Original Sixth's Stark Trek infantry could solo trillions of Signs Aliens while blind folded and limbless.
Edit: It's a joke
So you joke...