Seraph of the Sword was an obvious Limited bomb when it was first spoiled. Not only is Seraph of the Sword a 3/3 flyer that’s very splashable, but she can’t be dealt combat damage. This means that she could single-handedly block bombs - except things like Colossal Whale from the same set, which will just "devour" it. Even creatures with deathtouch can't affect Seraph of the Sword in combat, since at least 1 damage must be dealt for deathtouch to activate. It’s an easy first pick, hands-down. But since we're obviously not drafting Magic 2014 anymore, what does she do on her own?
Of course, Angel cards are always popular, and most tend to find a home somewhere. Seraph of the Sword would seem welcome in a wide array of Commander decks. However, she hasn't found many homes. You would think a 4-mana Angel would find a home, considering that there aren't all that many. But besides seeing play in the occasional Avacyn, Angel of Hope or Gisela, Blade of Goldnight Angel Tribal deck, Seraph of the Sword sees inconsistent play in EDH .
Is the Seraph good enough for Constructed play? As far as Core Sets rares go, this is in the middle of the pack. But there are just a lot better creatures that cost four mana in Construct, so it's little surprise that Seraph of the Sword never found a home in Standard. Outside of some casual Angel decks, there are just better options for this deck slot. However, besides the fair amount of EDH player, she does she play in some Budget Cubes as a creature who's solid on offense and defense.
While no one is falling over themselves trying to acquire copies of Seraph of the Sword, her price has been fairly consistent for the past few years. She's never quite hit $1, but has hovered around the $0.75 mark for quite some time. Seraph of the Sword is a card that could be reprinted someday, so if you're looking to pick up a copy, the best investment would be to pick up a $2 foil. Foil prices tend to stay more consistent, and this is a card best suited for a reprint in a preconstructed deck.
Really, the Seraph could see more Commander play than she does. Perhaps, someday a new Angel Legendary Creature will be printed that will be happy to run her on a regular basis. Until then, she's just a nice card to have in your collection