Nah. Remember weapon speed affects weapon damage per swing, so a faster weapon deals less damage per swing, which is very much not Ret's thing (or any 2H spec's thing). Now, IRL a two-handed sword had a pretty high "attack speed" because it would only weigh a few pounds and there were proper techniques involved rather than "swing it very hard", but game mechanics > realism.
Also, don't forget in all this talk of weapon damage & speed that most of our attacks are normalised - meaning the damage is based on a 3.3 speed weapon.
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In and of itself, I think Divine Steed is fine mechanically, and aesthetically is very cool indeed. I would buff it to make you immune to movement-impairing effects whilst it's active (remember the short duration too), but that's all.
The problem is that as a mobility tool for a class with nothing else, it is really, really bad. The cooldown is too long for most purposes, and the duration is too short. The fact that you can be snared/rooted etc whilst it's active also means it's unreliable.
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I'll be honest, watching Bajheera's (mostly) 3v3 videos, he's not done bad at all as Ret in the Alpha to date.
Then again, you have to consider the quality of the opposition. Bajheera is a RBG Grand Marshal, an Arena Master, ended in the top 0.5% in WoD season 1 & 2, and the same in seasons 14 and 15. In other words, he's a good PvP player. How many of his opponents are as good?
I mean, good players can very often take an under-performing class or spec and do very well against mediocre or bad players. Just to give one example, I recall seeing a warrior bladestorm Bajheera's ret paladin whilst Shield of Vengeance was up and he was sitting on the warrior's mage ally (who didn't dispel / spellsteal SoV). Shield of Vengeance broke, and the mage died.
Now, what happens if you factor in all the usual PvP addons and better players to this mix? If the mage doesn't just spellsteal SoV, he and the warrior can move away to let it fizzle. Instead of focusing on Bajheera's team members, they can focus on him, seeing as he has only one defensive ability that can't be purged or interrupted (and the latter will mess up his other Holy abilities).