Arcing depends on a lot of things. Voltage of the line, humidity, distance above sea level, etc.... Will the lines you are talking about arc? Probably not, but 1-5 feet away is too close. The standard across the board is, for most typical distribution voltages, i.e. 14-12 kV and below, you need to be at least 10 feet away unless you have very specific training for working in these situations. That distance increases at the voltage goes up of course. Now, 10 feet away does not just mean your body, it means keeping away from limbs within that distance, as well as keeping your tools out of that zone as well.
What are the dangers? There is indirect and direct contact. Direct contact is just that, your body directly contacting the wires. It might be your head as you poke it through the growth, you may take a swing and swing right into the conductors. Anyway it happens=bad.
Indirect contact might be your rope coming into contact with the conductors, or a limb you have cut and are still holding onto hitting the conductors. The possibilities are endless and with the same result as direct contact. Electricity is looking for a path to ground and in these instances YOU are the path.
At the least, severe dermal burns can be expected from contact with the conductors. At the worst, your internal organs can be basically cooked, either killing you instantly, or maybe a few days later.
In addition to personal safety, if you hit the conductors, you can trip the fuse, and depending on where you are in a circuit, you will knock power out to a lot of unhappy customers, including ones with critical infrastructure potentially. It may result in frying appliances inside someones house, or causing a fire in extreme cases.
That's my short version of the hazards associated with working around wires. Were you being reckless? Probably not, you just didn't know any better. You didn't get hurt so no harm no foul. But now that you know, I would practice at a park or a less target rich environment. Good luck and stay safe.