First of all, Let me start by saying that Harrow is not the most one that needs a rework/tweak, but I can say that his kit is sort of "out of touch"
Let me explain, His Abilities are based on Sacrficing Himself for the benefit of Others. Now, Lets look at how he actually is
1st ability is simple enough, a good crowd control ability that open enemies to easy headshots
2nd ability is not bad either, sacrificing Shield for Buff and Heals
3rd and 4th ability is the problem here, 3rd ability channel Harrow energy to give energy to others on Harrow Kills. Now thats a huge problem cause harrow is a support warframe, not an offensive warframe with damage abilities. his augment also doesn't make sense, Makes his 3rd ability to Give 40% Damage Reduction to Him and His Allies + 0.5 Energy For his Thurible Whenever he is damaged. Which doesn't work since people would either run of your 3rd ability range, or kill the enemies. which doesn't make this augment valid
4th ability is very useful if used correctly, and has been staple of Eidolon Hunts, it give a damage immunity to you and your allies in affinity radius and give back critical chance buff based on how many damage is stored. the issue is the same with 3rd ability augment, it require team to stand around, get damaged. which doesn't work in real game
So I propose these changes.
1: Make that Harrow 3rd Ability can be triggered by team kills that are in his radius.
2. Change Harrow 3rd Augment Completely, Probably give a damage buff based on how much Energy is used on the ability
3. Make Harrow 4th ability (although this might not sound right) take into consideration of self damage. Which could potentially fix Harrow 4th Ability Issue in normal runs
Thats all for now, I might see if Harrow need more Changes. Please let me know what you want to change for harrow