I agree with LisaG's description and would like to know what she asked, too.
The thing with a horse that is dull to the bit/hand is that you may have to get stronger/heavier for it to become lighter. A lot of people want the horse to be light to the bit, so they offer the horse a very light hand, but when the horse kind of does what you want, kind of turns, kind of stops, kind of bends, but is doing it the whole time leaning on the bit, braced in his neck, you are not building lightness. You are accepting the status quo. If that's ok with you, by all means leave it at that. Your horse would certainly prefer that.
However, if you want him to be lighter, (and in time he will MUCH prefer this, once he understands what a good deal this will be for him and his mouth) then you have to be firmer than he is bracing. You cannot just meet his resistance and then let go while he is still resisting. The place where you let go is what you'll get next time. The reward must be given at the place where HE LETS GO.
So, you may have to get quite firm to make him become willing to let go.
For example, let's say you ask him to stop. You take up the reins (I am not talking here about the seat, but of course, you would put your seat into a "stop" position very first) and you kind of close your hand firmly around them. Horse feels that "stop" on the reins, so he leans on it. You feel him leaning on the rein. (by the way, I always have a wee bit more contact on one rein than the other in any stop). You become firmer, he becomes firmer. You make one rein even firmer and raise it a bit. You don't actually pull the horse's head off to the side, buy you put on as much pull as the horse is , and one ounce more (as per my trainer's instructions) . Wait a bit. If horse adds more, you add more . Wait abit. Do not release until HE gives to the bit, even a bit. Then you can reward.
It's the studied and careful use of of ONLY rewarding him when he responds softly to the rein that builds in softness. Never reward him with a release if he is still leaning on the rein. But never fail to reward even a small give on his part. You dont' always need to fully release the rein. Sometimes a small release will give him the idea of what he needs to do to get lightness from you.
Once he knows that he can get a release from the rein easily by giving to it promptly, he will much prefer that. But you are required to be vigilant to both reward him (never ride the brakes , so to speak) when he gives, and to insist that he gives before he earns a reward.
YOU build in lightness, but the horse will EARN it .