samsung s4 l2_hsic wakelock is draining all my battery

This is a good explanation of what it is and why it's necessary. (The author obviously has English as a second language, but it's still very readable.)

As he says, the only thing you can do right now is turn on Airplane mode. You'll have to wait for Samsung to come out with another update to 4.3. (There have been 2. If you only got one, this fix may be in the second. If not, hope it's in the third.)