Older heroes really suffer from lack lustre traits. Compare Nazeebo to Lunara, for example - he has three of talents that play off his trait, one of which is mandatory, the other two are pretty poor. Lunara on the other hand is built entirely around her trait, with multiple talents and abilities that key off it. Their design of heroes has come on in leaps and bounds since the early Alpha.
RE Tyrael, it honestly feels like they just need to bite the bullet, make half of his talents baseline in his kit and then rebuild his talents based on the role they want for him - either as a support warrior or an engage warrior. His talent trees are full of utterly garbage talents that do very little (shield on death explosion, damage less abilities on death, etc etc). Make some of that baseline:
- When he dies, his explosion should also shield allies
- Talents for his shield will also affect his allies
- He can use abilities when dead but they deal no damage
And then build the trees so you either go support (Stronger shield, durability, peeling skills) or engage (Holy Ground, better teleport, slows). That gives him two solid roles and a much more interesting kit, and at least makes his trait more useful and removes all the stupid talents he has for it.