The first thing that needs to be said when talking about old school methods is the amount of times that you train a body-part if you want to put on muscle. Without getting into a scientific argument about recuperation, over-training and muscle physiology you simply cannot build muscle by training it only one a week. The same applies to your arm workout, if you want to get bigger arms you need to hit them hard at least twice a week otherwise you will just not get results. However it also depends on how you train your arms and doing negatives and forced reps with your arms is not a good idea.
You need to get that “pump” if you want to get growth in your arms and that means working with a lighter weight and doing more reps. It might be a good idea to try doing triceps and biceps as an alternating superset to see if it works for you but that is only one option.
The great Serge Nubret was someone who sculptured his body to perfection by doing lots of reps with a lighter weight instead of always getting to failure after three or four reps. Serge would do 8 sets of 12 reps each to ensure that he got the maximum amount of blood into the body-part he was training.
It is a good idea to start your arm workout doing 12 or even 15 reps so that you get the pump going. As you start to get weaker you can lower the reps and even go below 10 reps as long as you make sure that you always keep strict form and only work your arms and not your back.
This isolation takes a bit of practice but it should be something that you apply to every body-part that you train. In order to get results you need to be able to effectively isolate only the body-part that you are working and nothing else and this takes concentration and focus.