What 343 could have done to fix the Warden Eternal

Hi all,
I was playing through Halo 5 on legendary throughout the past few months and found out how terrible the Warden is. This got me thinking about what 343 could have done to fix him and not make it everyone’s worst nightmare. These are the things I have so far, feel free to comment some things they could’ve done.
-make you fight him only 2-3 times instead of 7
-have the AI squad able to properly fight him
-The warden should get an extra power/attack every time you fight him to make it less repetitive
-Make the hard light sword not a one-hit kill (except on legendary)
-Further explain more about why he serves for Cortana