Regarding the clips:
The first one is clearly a mistake, the hit detection in this game is to blame, not the Sunbreaker. When the Hunter stood close behind him his hitbox must have triggered the hammer.
As for the second clip, then one with the Titan hail Mary, it's just that, a lucky throw. Saying the Sunbreaker is OP because he got a lucky throw would be like saying the tomahawk was op in call of duty b/c you could get cross-mapped with it.
Now check out this one:
http://xboxdvr.com/gamer/Alpheus%20belulus/video/10324704
English
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Thing is about the second clip he popped his super with very low health and should have been punished for bad activation. and the fact that he had so much time to roam a bit and then launch a hammer across the map. TLDR: tons of armor and health regen, Long timer, Massive range. Just saying. That TLW clip is impressive though.