Like most others I’ve seen, I like the idea of having the set bonuses on heirlooms. It’s a cool idea, and while the ones initially given seem cool at first glance, they are quite lackluster when thinking about them.
Some potential solutions being as likely stated several times by now as replacements:
(2) Set: Rested experience consumed is reduced by 30%. (I don’t mind this, but as stated, for most veteran players, IE, those with heirlooms, it’s pretty useless in it’s current form. If you wanted to keep this. I’d suggest changing the 6 set to benefit it. Otherwise, some other general purpose bonus would be better.)
(3) Set: Increases your out-of-combat regeneration in the outdoors, normal dungeons and battlegrounds. (While sounding great from a classic point of view. It’s pretty much useless in the modern versions of WoW. I’d suggest move speed/mount speed or some other general purpose stat. Like versatility, or even health/mana when earning exp. (like the trinkets do.) )
(4) Set: Gaining a level triggers Burst of Knowledge, dealing Holy damage to nearby enemies and granting you 40% primary stat for 2 minutes. Defeating additional enemies extends this effect, up to 2 additional minutes. (This one is cool, but the duration needs to be boosted drastically. As stated prior, quests/dungeon rewards/BG rewards are what is going to level you most of the time. Which means you’re likely away from mobs where this benefits given it’s duration.)
(6) Set: Rested experience consumed is reduced by an additional 30%. (Given this is the 2 set as well. My suggestion as mentioned earlier, if you wish to keep the idea of less rested exp lost. Perhaps make this 6 set piece something like. ‘x% of quest exp gets turned into rested exp.’ be it a small amount would go far. Or, even as others mentioned, ‘gain rested exp at a faster rate/outside of cities while out of combat.’ )
None of these give massive boosts to gameplay, they’re not game breaking levels of OP, but they don’t need to be. However, the current(original at the time of writing), suggestions, seem weak at best, or nearly worthless at worst.