I consider one of the primary goals of lighting outside in daylight for ENG to be getting light into the eyes. Especially on a perfect overcast day, having the light coming from directly above will cause shadows in the eye sockets, and the eyes will go "dead." Even if your camera light with a dichroic is not strong enough to actually fill in those shadows, just the tiny reflection of the light on the eyeball itself will help put life back into dead eyes. Reflectors work for this purpose also, even on overcast days.
Positioning your subject is probably more important than what lights you use. You obviously don't want to put the subject in the shade with a bright background. But once you have the subject positioned, look at what the light is doing on the face. Are the eyes dead? Fill them in. Does your subject seem to blend into the surroundings? You might hit him with just enough light to "lift" him out of the background. Experiment with the lights you have and see what works. If something doesn't work or takes too long to use, change to something else or modify how you use it.
Also, realize that a light that is too weak to significantly impact your exposure may still serve a purpose. You may not get enough exposure to affect your iris setting, but the light may still give just enough to soften an unwanted shadow or give a little lift to the subject. Or it may just give a reflection in the eyes. If your own eyes register any effect from the light on the subject, it may register on the video as well.
Try to avoid spotting down a light to the point that the fall-off at the edge of the spot can be seen in frame. Sometimes, in order to compose a shot with something specific in the background, photographers will end up with the subject either backlighted or in a dark area against a bright background, and they'll try to compensate with lights that aren't sufficient to fight the sun. To get enough intensity, they'll spot the light down on the subject's face; but the resulting circle of shadow across the chest or neck looks terrible. If you get this result, either add more light by using another lighting unit or reflector, or move to a different location that is friendlier to your shot.
Personally, I have an HMI, and it's a godsend. When I didn't have one, I often used a reflector on a stand with a Bogen arm holding it. When it was too windy for the reflector, I just used Lowel Omni lights with dichroic filters and stacked the lights up next to each other if I needed more intensity. If all my wishes were to come true, I would have silks and scrims to fly above and around the subject to knock unwanted light off my subject, as "Actually" suggested above. Since I don't have those, I have to choose camera positions that solve those problems.
Play with what you have and let us know how it looks.