Sharpness

In essence, increasing sharpness makes the filter more dynamic which will lead to less filtering. It reduces over-filtering.

More technically, sharpness effects how much of a dynamic multiplier gets added to the base filtering value. For example, considering IMUF/Gyro LPF's, at say 50hz it doesn't have to do as much to increase your filtering frequency as it does at 10hz. At 10hz it needs to boost that base filter a ton more to give you more snappy feels and better propwash handling. But that lower base helps by in a sense overfiltering when it isn't a problem and then filtering less when overfiltering would be a problem.

Generally it's a good idea to turn Sharpness off while trying to tune: set sharpness = 1. Such will allow you to tune Q without additional dynamic changes.

Once a good Q range is estimated, then one could introduce sharpness. As more sharpness is introduced, Q should be reduced.

Generally, but not always, a few good options are:

1. Sharpness off; only tune Q.
2. very-low Q; medium-high Sharpness.
3. high Q; very-low Sharpness.

Generally, you do not want high Q with high Sharpness -- i.e. Although good to not over-filter, you also don't want to ultra-Under-Filter.