Question: First of all I just started doing barre chords after learning ordinary non-barre chords. Problem is they don't sound so well, so my question is, will training with hand grippers help me achieve this? Because I've been applying equal pressure and they still sound a bit off, only a bit off.

Answer: 
No, training with hand grippers won't help you execute barre chords. Firstly, time spent squeezing grippers is time that you could be using to actually practise barre chords. Secondly, the physical action is markedly different and not about finger placement and subtleties of pressure. But hey, you could end up with a really impressive handshake, and all the other musicians will ask you to carry their gear. It's early days; hang in there and your barre chords will improve.
I don't find those hand-grippers very effective in teaching you how to make your barre chords sound better. The truth is, a large part of getting your barre chords to sound good comes from good technique. There are quite a number of tiny details that will help you achieve a good sounding barre chord with minimal effort. Many people think that in order to get your barre chords down, you need quite a lot of strength, and that is not true at all. Remember that precision beats power. Focus on getting the details of the technique correct. 

Another thing that may be preventing you from getting your barre chords down is your guitar's set up. If your strings are too far away from the fretboard, you're going to have a really tough time getting your chords to sound good. Make sure your guitar is properly set up.