this it nice but
Sentinel is too weak... because his keep get stun too easy, after he get stun by a combo he will get stun again and again with the same combo. it is to say if he get stun just one, he alrady lose

he shouldn't get stun again untill he regain control.
stun shouldn't use as a safety to get away from combo, it should be a weakness that you try to avoid not try to get stun just to break of combo.
and for Onslaught he movement a little fast and with those power it a little overpower but I don't mind if you like it this way.
Also "All the throw issues have been fixed" is it include issuses about other try to throw and custom state Onslaught ?
because you don't use hitoverride many attack don't make any damage at all.
exsample "Misogi" lv3 super of ShinGouki of PotS this move will put you in custom state when it hit.
but your Onslaught just selfstate (that what i think) out of it so it take 0 damage.
and that include many other attack that not a throw but use targetstate.
As he is right now it kinda like a broken cheap char. so try to use hitoverride.
what more.. I don't know what did you do but some attack of other char deal less damage that it should. when your char deal this must damage you shouldn't give him to must extra defence.
for now it no fun to fight Onslaught at all. most of the attack seem to cause no damage. it feel like fighting RareAkuma, a joke char that to have fun but can't get fair fight out of him.