Levers: Hammer weights and travel parameters get amplified or de-emphasized depending on the geometry between keytop and hammer crown. Generally, weight reduction at the key equals loss of hammer rise, and each of the three main levers contributes to this as a give and take. Their relative impact varies, of course, so we benefit by having a well-observed hierarchy in mind as we decide what to try.
How much can weighoff help grand action playability? Sometimes, as with poor action geometry, weighoff will not help unless problems are corrected first.
I recently I found myself so challenged by a vintage Baldwin L. The hammers, shanks, and whippens had been replaced and were in good shape. But the action did not play well. My customer wanted to know what could be done for her attractive instrument that played like a truck and no longer held its tuning. I recommended the fairly expensive route of new belly, block, and strings, plus deep regulation, which she agreed to.