Although some folks do it, I personally think 220 is not far enough..... I would go to at least 400 hand finish, and preferably 600.
Did you dilute the ferric with distilled water? Generally the best etch comes when you dilute ferric either 3 to 1 or 4 to 1 with distilled water (that means 1 part ferric, and either 3 or 4 parts distilled water. When it comes to etching a blade with ferric, the slower the etchant works, the better the end result. I personally use a 3 to 1 dilution, and with an ambient/etchat temp of approx. 70F, it's generally 5-8 mins for straight steels, and 15-30 mins for etching damascus....... larger, more open damascus patterns get a shorter etch time, and finer, tighter pattern get a longer etch. In the end, it all depends on what you are seeking.
I can't overstate the necessity of absolute clean. I put on latex or nitrile gloves....... I clean with acetone, then a second time with windex, and then after wiping/drying with a clean blue shop paper towel, I air hose it off to ensure ALL the windex is gone (a single drop of windex will kill an entire container of ferric).
From what I can see in the image, you've got three different zones of hardness in the blade..... the edge, a transition zone (the middle), and a soft zone..... near the spine, close to the handle. It's likely that you will still see a few etched in scratch lines with a 400 grit finish, and even less with 600. I have gone as far a 2000 grit hand finish, but generally reserve that for finer patterned damascus blades. With straight steels, 800+ can be a bit tricky, as it will sometimes produce a "smeared" type look after etching.
Since there are a wide range of variables from shop to shop, it's rare that an individual can read up on etching, and make is come out as expected the first time..... it takes a bit of experimenting to achieve the specific finish you're after.