Because story wise, Varric only uses Bianca. They let make him use daggers for gameplay purposes and player choice - but he uses Bianca as far as story/lores concerned you know? Also it only effects the Bow skill tree. As they have said all specializations are universal for any style, they don't care if your using daggers or bows, it's all universal - that skill isn't. It's like it was designed to BE in the bow tree, but they don't have focuses IN any trees other then specializations.
All of that, ultimately, leads me to believe that companions have there own special focus the player doesn't get. Or different takes on similar focuses that just give the companions their own flavor on the specialization while keeping it the 'same' as the inquisitor's. Either way, it's all speculation on my part - but even if all the other companions have matching Focuses, I'm still 99% certain Varric's is his alone.
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Ehh, I don't think there will be anymore rage then what's there right now. I think the issue, atm, is people are obsessive over the idea of things not changing and can't picture how any change could be good. I mean, a good tank shouldn't even need to be healed on small encounters. Big encounters, sure, but like any focus skill resurgence is designed to be a turn the tide ability. It's not a a general fight heal or after a fight heal it's a, your fighting a Dragon, 2 of your party members are down, and you need to just 'reset' things. Resurgence will do that for you, it'll revive everyone, put em all at 100% hp and put up a regenerating well for a few seconds.
REALLY useful, you know what else is useful? Slowing time down to a crawl where your entire team moves normally for like 10 seconds letting you dump out intense amount of damage and reposition completely free. In fact I would imagine the Inquisitor abilities are the more powerful of the lot. Group focus'ed vs individual focused.
Varric's, as an example, just doubles his skill use. Explosive Shot? Great you fire 2 now for a limited time. It's basically X2 skill use dmg (maybe also auto-attack fires 2 arrows not sure). Either way that's great but its individual. Solas seems to be a Firestorm, which is also an individual thing and not group focused.
Just a mild speculative guess on my part, Inquisitor probably gets the more powerful focus skills that end up being group oriented. I hope it I'm wrong, mostly on that one as I want Reaver to have a Rage which would definitely be singular focused.
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Just thought of something imagine, if you will, Varric using his focus as Inquisitor uses Haste (or slow time, whatever they call it). Varric gets double dmg vs the super slow-mo easy time Focus use. That could be pretty devastating.