Every time I talk about a Tear or its related items, a firefight breaks out...I use the Expanded Mind mastery with Pantheon, and Manamune mixes well with it (mastery is there for the item, not the other way around). It's pretty nice; once I get it, I can use my e to gain 5 mana. Idk why it works like that, but it does. And I chain spells and attacks well enough together that it goes up pretty darn fast. I know Pantheon's squishy, so instead of focusing on making him a bit more defensive, I build into Manamune to harass enough so that enemies don't get near me. Yes, I know it won't always work, but it's nice enough. It allows me to not have to play conservatively with my spells, and I throw spears at anything remotely close, lol. This allows me to kind of replace my autoattack with my q, making me a pseudo-ranged champ.
To be fair, I haven't really tried to be conservative with Pantheon's mana, or use a different build, so I'm not here to knock what works, and if you say that Panth doesn't have mana problems, vonFielder, then I will take your word for it. I personally happen to like being aggressive/spammy with Pantheon's abilities, so I decided to build an item that let me does that without sacrificing AD. It keeps me out of the direct fray with most champs, helps me stop CS, etc. I even spam my abilities to farm from time to time (no worries, I never find myself regretting that, what with my CDR). I do get the CDR boots, but sadly most games don't last long enough for me to build more CDR, as I usually end up with Manamune/CDR boots/TF/the pieces to IE, and the game is over. I've thought about either Ghostblade (ArPen is nice, as is the extra everything else) or Frozen Heart (the armor Panth desires, in addition to more AD through Manamune, and a nice passive, as well as enough CDR to bring me to a comfy 38%), but again, I never get that far.
I admit that I just really like the Tear items, even if they aren't suited for every champ, so there's definitely bias on my end. It just doesn't seem as bad as it's being portrayed as, especially if it is my goal to spam q as often as possible.