D.S.
ok i have a special needs child with a severe language barrier too. and first and foremost i do believe in swats but i dont swat my special needs child. you cant do that with a special needs child they dont understand why they are getting swatted for being fustrated. QUIT SWATTING. keep signing and try pecs with him. everytime you say drink sign drink but with his visual impairment this will make this harder. put his hand on yours when you sign to him. i have been suggested several times to watch the helen keller movie my ds has hearing issues.
what you are considering a bad temper is probably a fustration tantrum. my son does them alot. you have to kinda ignore them. when they cant communicate they have temper tantrums cause of it. when you say no sign no and put his hand on yours when you do it. make his pecs very large or small what ever he needs.when you quit spanking i think the throwing things and hitting will quit. he cant get you to understand and you are hitting him(swats) which makes him more fustrated and so his only outlet is to hit back. or throw whichever is more convient. mine throws things to when he gets mad at his toy or whatever if its not playing right. he used to throw his tippy at us for more drinks. we firmly tell him no and sign no too. he has no way of communicating with you. put yourself in his shoes if you couldnt talk and had problems seeing how would you get your husband to do what you want and when he didnt do what you needed or wanted you would get mad and throw things too or hit. and you hit him lets say your husband hit you for not being able to talk or tell him what you wanted or needed. time out does work for my son but i use them sparingly. when he is having a fustration tantrum i ignore it. when he is having a defiance tantrum i put him in time out. i have to hold him in that one spot and keep telling him no verbally and in sign. you need ot get him to developmental pediatrician. YOU NEED TO HAVE LOTS OF PATIENTS WITH HIM. you can not treat him like he is "normal" because he isnt. you have to take his disability in to serious consideration when dealing with him.
get ahold of your school system and check into ppcd through the school system. and tell them you need serious help with him. you have to get patience and quit punishing him for his lack of communication that is not fair to him and he has no way of saying it. when mine does good since he has hearing issues. he loves it when we raise our hands in the air and say yeah instead of good job. when we do that he knows he did good and he will clap for himself. if he does a good job clap for him and if his vision is real bad you hold his hands and clap them for him so he knows he did good. or raise his arms in the air and say yeah real loud. so he knows he did good. he will start mimicing you. give him lots of rewards by clapping or raising your hands in the air and yelling yeah. he will be so proud you will see his little face light up. because he is not getting hit for bieng bad it is a way to praise him for doing good.
do not do any more time outs than absolutely necessary. donot punish a fustration tantrum. because if you put yourself in his shoes you would do the same thing. time outs are for absolute looking at you like I DONT WANT TO DO THIS AND I KNOW BETTER AND AM GOING TO DO IT ANYWAY. please please please learn patience with this child. and lots of it