She is good offlane but she falls off so hard later in the game.
Her third heal is pretty weak since she doesn't have attack speed nor lots of dmg. The Crit isn't even that good starts at 120% and ends at 180% (220 with lvl 20 talent). But the big issue is that at lvl 20 the 2 starbreaker charges talent is much better than the 40% Crit one, since her getting 40% boost doesn't really help DPS more than 2 dawnbreaker charges.
I suggest a crit buff to something like 140/160/180/200 and 240% with the talent.
Secondly her fire trail dps is pointless but the real point of the ability is the slow of the trail, but it's really easy to avoid it since the path is not wide, so something there needs to change.
Finally her ulti cast time when coming down is abit too slow, very very easy to dodge. A slight animation time reduction should be a big buff.
Some random ideas for shard/aghs: this is off topic
I know it's still early but even at higher skill brackets than Archon and crusader, the hero is struggling.
Shard idea:. Switch place with hammer throw or buff healing from third.
Aghs: Lower Ulti CD and longer stun by a second
Source: https://www.reddit.com/r/DotA2/comments/moenod/just_some_feedback_on_dawnbreaker_abilities_as/