If there's arcing, seems like the coil is making a higher voltage.
Arcing at the coil suggests that voltage's usual path to the distributor then out to a plug isn't intact.
- First check would be to disconnect one ignition wire and then reconnect it. Repeat until you've done that to all of the ignition wires. Even if it starts, observe the top of the coil again. Look along the length of each wire, to see if there's arcing out of a defect in the wire's insulation.
- Next (or while this wire is off) would be to remove the coil-to-distributor wire, check the ends for detects/damage and check its resistance with a meter to check for continuity. If that looks good, I'd connect back to the coil, then check the other end for spark to confirm the voltage is getting as far as the end of that wire.
- Look for carbon "tracks" on or in the distributor cap, and any damage to cap or rotor.
Is this a new growing or sudden behaviour, or have you just/recently changed coil, ignition module, wires, plugs, cap, distributor or ____?