When they are outstretched in this fashion it shows the desire and zeal that you have to help others. You are the type of person that thrives on helping others and making the world a slightly better place through whatever small kindnesses you can do for others. This dream is a reminder of that and probably a call to action if you have been rusty in your craft lately.
Seeing arms could also be a sign that you need to be more aggressive. An actual human arm or the weapons that make up the other definition of the word, it does not matter which one you see; in this case they both have the same meaning. You need to arm yourself and protect yourself from whatever may be out to harm you in the future. This does not literally mean that you need to bear weapons with you, but it does mean that you should be on guard in case something funny, unexpected, or dangerous happens to you.
If you have a dream where one or both of your arms are injured, it means that you need to watch out for yourself better in the future, and that you are incapable at the present time of handling your own care. You have taken on too many burdens and are too busy handling other people to deal with yourself. While these exploits may sound noble, in the end it works terribly for everybody. This is because it confines you to a position eventually where you are able to help nobody, even yourself. When you reach that point, you aren’t doing much good to anybody. While well meaning in the beginning, you put yourself in a situation where you weren’t really helping anybody, and because of it, all of those that depended on you in the past will not be able to look to you for help until you get back on your feet. Take some responsibility for yourself too. Selflessness is nice, but you are just as important as anyone else is, and it is no excuse to devalue yourself for the sake of others.
To dream that you were hurting someone else’s arms means that you are very displeased with them, even to an extreme degree. The reason that you are dreaming about it though is because it still plagues your thoughts. You will never able to get your grievances off your chest, so now you have to sit quietly and watch them get away with whatever it was they did to make you so angry in the first place. Even if it is something simple and seemingly inconsequential a dream like this lets you know that you do not truly feel this way. Make your feelings known so that they can attempt to correct their mistakes and so that you can get back to your life.