The ignition coils draw a lot of power, so any resistance makes a voltage drop (Ohms law again). There's a lot of wire and several switches in the ignition power circuit. I doubt if your 0.7 ohm reading is accurate though - reading very low resistance is tricky. With your meter on ohms, touch the probes together. There will probably be some non-zero reading, you have to subtract that from the reading of the wire. Analog meters are capable of being zeroed but are not very accurate at low low ohms readings. You need to use a Wheatstone bridge to accurately measure such low resistances.
Anyway, .7 ohms with both 3 ohm coils powered - worst case - at 12 volts is 8 amps load... 5.7 volts lost just in that one wire. (OK, it's more complicated because you would only have 6.3 volts now and thus only 4.2 amps... but then the drop would only be 3 volts ... oops that's a different voltage and drop and everything changes again and my brain hurts...). Whatever, 0.7 ohms per wire is unrealistically high and you'd have very big problems if it was right, some circuits go through several of those wires plus connections and switches.
The harness wire is approximately US 16 gauge size (it's metric and not exactly the same) and has about 0.005 ohms per foot resistance. That's 140 feet to get 0.7 ohms approximately.
The connections, those bullet connectors, have a resistance as well. With clean tight ones this is negligible - but corroded ones have considerable resistance. Resistance + current = voltage drop across the connector. It also equals power and thus heat at the connector. You will likely see many of the plastic sheaths over the connectors have blackened and are not clear plastic any more. This is from the connector heating up and burning the plastic. If the metal gets really hot it loses it's temper and springiness Then the resistance gets even higher, and things can get smoky and maybe flamey.
The same thing happens to the switch contacts, but at leats they get switched - this helps clean the metal contact via them wiping against each other. Short of opening the switch (careful as springs and contacts WILL shoot out) you can get cotact cleaner spray and spritz some inside, followed by some spirited switch turning to help clean the contacts. Once the switch gets seriously resisitive it will overheat and melt/burn the plastic housing and be ruined - this rarely happens though because of the cleaning action during use.
Best thing is to carefully clean all the bullets, male and female. They should be shiny, but don't use sandpaper and remove the tin colored plating to expose bare copper - the copper corrodes quickly and you'll have a new annual chore of recleaning them all. Contact cleaner on a cloth works for the males, a Q-tip works for the females. Use smooth jaw pliers to gently squeeze the female contacts a bit tighter (serrated jaws will cut the plastic sheath), squeeze across the gap so as to close it... not on the gap distorting the cylinder. Put some "dielectric grease" on both male and female ends before reassembly, this helps prevent corrosion but doesn't impede electrical performance. Any auto parts store will have this grease.
The splices do look like factroy work to me. If you look at the Honda (NOT CLYMER OR HAYNES!!!) wiring diagram you'll see where wires are spliced, they show dots where wires meet to indicate a splice. These are rarely any trouble, the wires are soldered and taped over.
