I'm looking for novels where hidden weapons like sleeve darts, poison, needles and etc are used. The main character should use them. I've heard of doulou doulou already
Gate of God (though its not primarily about his hidden weapons but he is shameless so uses these tactics)
Killing Grounds of Gods and Devils has a character that specializes in hidden weapon (throwing bisturis to be exact)
Everyone Else is a Returnee, in some portions he uses weapons hidden within his armour like spikes etc
Really, m8? He said in his post that he already knows it. I mean, he got the name a bit wrong, but it should still have been obvious.
The Strongest System. He uses a brick as secret weapon. His main attacks are plucking and kicking balls.