All Templar abilities... no Lyrium addiction...
Well, it doesn't say that she doesn't need lyrium, the Seekers are probably just better at regulating it? Which doesn't make much sense, why not share that knowledge with the Templars? Do the Templars take more so they are stronger? Maybe it is like Alistair, still able to do some abilities, but not as strong without taking lyrium... maybe?
That description is just confusing, why not have Seekers become as addled as Templars if they take lyrium?
Well, historically speaking the Seekers of Truth have been the "über-Templars". They were the guys the Templars called in, when the Templars weren't equiped to handle the situation. So we can be pretty much certain that the Templars are not more powerful in their abilities than the Seekers. If the Seekers and the Templars are moving (storytellingwise) further apart as organization, being more distinct from eachother, then it makes sense that the Seekers wouldn't impart ALL their secrets to the Templars, so that the Seekers would remain relevant.
Malvernis is not soloabe because he can cause instant death every couple of minutes. Given that during soloing you will lack damage he will cast it and you will die. Actually one of the game's greatest challenges is doing this boss without Anders/healer Hawke on nightmare, its not soloable really.
Sorry I messed up the mechanic its 30%, I used some balancing modes of my own so I had to revert to vanilla. But it pales in comparison against the cooldown mechanic. Anders has 10% cooldown reduction as a passive spell named "swift justice". However this is the significant part:
Do you see the synergy between these spells? Anders will relentlessly cast spells by sacrificing health and he gains it back by killing enemies. Martyr has no cooldown and it reduces all cooldowns by 20% percent, so its even more effective on spells with higher cooldown. I have personally cast 5 chain lightnings while Hawke was still waiting for first cooldown to finish. The potential is limitless, you can permanently cast arcane prison on a strong enemy, cast inferno and tempest two times before the first one finishes raining, Heal every 10 seconds etc...
As for Aveline, she can gain 40% to all elemental resistance plus 10% magic resistance from defender tree. She also gains 25% damage resistance from her unique tree as well another 5% from defender. Damage resistance works against both physical and magical attacks They are more than enough, if not she can benefit another 20% from mage aura. More than this much magic resistance is unnecessary and overkill.
One of my my motivations for not really playing templar or tank was Aveline. She is just too good, when proper talents are given she is immortal because she can never be killed until the cooldown of potion is ready again. Her reflect is also very significant in terms of damage, something tank Hawke sadly lacks. And the fact that she can reduce damage takes by 50% on a character and transfer it to her self is the most significant talent in the game, and its 60% for Hawke if Aveline is a friend. Aveline is everything. BTW I keep switching controls because I find it fun and it adds variance to the game.
Malvernis is still soloable. There is just a timetable. And iirc you can even avoid his insta-death "spell", it certainly isn't mapwide. But yes, Malvernis is one of the hardest bosses in the game, no matter how you play.
Yes. Anders does have a high dps. But he is not very versatile. Hawke is. That is why I will always rank Hawke higher in all scenarios.
The defender tree is also available to Hawke, so that is not something that speaks in favor of Aveline. The ONLY thing she has going for her, that is unique, is her own spec, and that offers no real benefits that a Hawke cannot outweigh (other than bodyguard which admitedly is really good, though it can lead to a very dead Aveline quickly). Retaliation may be nice on the lower difficulties, but it isn't even a drop in the ocean on Nightmare. Besides you shouldn't bring a tank to deal damage anyway to begin with. If you want your warrior to deal damage, then better bring your berserker/reaver, than Aveline. And while Aveline does get a high damage resistance, it is as you said yourself, often negated by enemies, and with her inherently low magic resistance, she will take the full damage of the spell.
Of course, if you aren't playing a warrior Hawke the entire point is moot, since you won't have any alternative tanks.