Weaknesses?Like tanks,planes,ships...and so on,ultimately they are base on money and no one can conjure money,can't you?
No offence,i think the biggest weakness of vietnam military is its strategic goal.Your ambition is far more than your ability,you aren't Japan(We have a common and happy border,don't we?) and even Japan can't achieve during the weakest time of China.
So you can't "unify" indochina under China's monitor.Actually no matter how powerful you are,you are the weak when you face China.Actually,i don't think that Vietnam has to retain such a big scale army(compare to your economy).Big scale army is a heavy load of your country and your government has to permit the "military business".We all know what will happen in "military business".(Corruption,corruption and corrruption)
In my opinion,vietnam should reduce its army scale and update their weapon system.NO ONE will attack you(unless you want to "unify" indochina.),because any invasion to vietnam is not ecognomical.