Resistance soldering.

I was discussing thes with a co-worker and he said he saw one for $20 US on an infomercial. I don't plan on lots of soldering but there some PE/wire items that seem to need more than superglue so maybe one of those might be alright. Or get one to try before investing in an expensive one.
My smallest regular soldering iron is only 4 watts but that is too much at times.

I have a friend that scratch builds brass items for his model railroad and he has one. I've used it a couple of times while helping him on on his railroad. Usually for attaching the electrical leads to the rails - really liked it, heat stayed very localized, soldered joint was very neat and you didn't use as much solder. Item got cooler quicker because the heated area was not nearly as large as what you get with a regular soldering iron. I would like to have one but don't do enough soldering to justify the cost.