Your assumption is correct; the assassin's weapon was a very small
one...limited power, and a charge-up sequence that becomes longer the
more it's used. If the Minbari had shot Lyta, it would've taken too long
for the gun to power-up again for him to shoot Sinclair...and he would've
been captured. We slightly expanded the power-up whine for each shot
after the first one. You'll note that the first shot, the one that takes
out Varner, is almost immediate. Points and fires. Gradually it takes
longer, and finally the gun runs out altogether (which is why, though we
probably should've been clearer in showing this, the assassin finally
went hand-to-hand with Sinclair...the gun was never meant as an assault
weapon, more as a derringer, with a few shots in case he got into
trouble).

jms