In flashlights, lumen is unhelpful by itself. It only tells you total light output. Information like candela, spot size, and distance of throw all need to be known in addition to lumen. The higher the candela, the brighter the spot will be. Candela and lumen together can tell you how intense the beam is and generally how wide the beam spills to the sides. Spot size and throw distance are calculated roughly from the lumen and candela and also take into consideration the parabolic angle of the concentrator/reflector.
For a search light, spot is critical and long throw is needed so small spot, high lumens, super high candela makes an excellent distance search light.
For an edc flashlight, a flood like characteristic with lots of light is helpful - medium lumen, low candela, large spot, low throw. For defense weapon, a spot like characteristic with lots of spill, medium total amount of light is most helpful - high candela, medium lumen, small spot, short/medium throw.
Most good flashlights should give you at minimum two of the four parameters with at least one being lumen. If they do not, I would stay away from them unless someone with quasi quantitative experience steps up and recommends it. Preferably, spot size, candela, and lumen are given. This is enough to give you an idea of the shape of the beam and how much spill there is vs. How intense the light is on the spot.
For weapons, any offering from the well established defensive weapons light companies will be fine as they already tuned the parameters to best fit cqb situations. For laser, my opinion is it is not all that necessary unless the sights on the gun suck - like a jframe used as backup daytime gun... Lasers can be difficult to pick up at night within the flashlight aura because the flashlight also blinds you to an extent and also hides the laser. If the spot of the flashlight is sufficiently small - chest size at 5 yards, then that is all you need for aiming purposes so long as you also verify at the range (should be OK). As with anything, try it at home at night with safety checked gun. I find that flashlights leave me partially blinded or at least have image retention hindering my vision partially.