finally someone who recognizes the greatness of nuetral grip! I had a summer where besides flat barbell benching, my over head incline and other flat presses were all nuetral grip, its perfect for shoulder injuries, i have some bad shoulders and these shits never hurt them... AT ALL! IT also slabbed a ton of muscle on my triceps, within a month i had people ask me if i had gained weight just on my arms.... shits nuts.
Anyways, fucking do it, its dumbells, u could do one arm at a time if u really want to focus on ur weak arm that will help. Another good variation is the dumbell floor press, that will force u to activate ur trceps in order to start from the dead stop.
Also imbalances canbe from deeper issues that wont be fixed by working the weak arm more, in fact some injuries and imbalcnes will get worse with extra work, if u do not see succes by using one arm work and just genral stregnth gains i highly reccommend that u search for a deeper reason ur weakness and imbalance and the internet is not the FUCKING PLACE FOR THAT SHIT