Leave the scissors at home, they’ll almost certainly be taken from you on the first Singapore or Thailand visit. Nail clippers have never been a problem for me. Weight won’t be an issue if it’s a backpack/rucksack (I’ve travelled to almost every country in Asia, SE or otherwise, with a backpack and never had it weighed) but I’ve seen companions’ trolley cases weighed and some SE Asian carriers have quite low weight restrictions.