If your opponent is playing a fast deck, it makes sense to remove some of your expensive card advantage or slow top end cards for a mediocre two drop or cheap play that can help you stabilize
Sure those landfall payoffs are good, but controlling a certain number of lands has benefits too, Sylvan Advocate, Fecund Greenshell, and Crash of Rhino Beetles get better if you control a certain number of lands
Pennon Blade is a SUPER clunky card, it would be nice to play Stoneforge Masterwork, but this isn't a Squirrel deck
Throne of Eldraine A fantastic inclusion to single-color or even two-colored decks, Throne of Eldraine is an expensive mana rock that adds a ton of value to your mana base
Check out the mechanics article to learn more
On the Play: -2 Shanna, Sisays Legacy, -1 Song of Freyalise, -2 Trostani Discordant