Auriok Glaivemaster

As long as Auriok Glaivemaster is equipped, it gets +1/+1 and has first strike.

Veteran Armorsmith

Other Soldier creatures you control get +0/+1.

Bone Saw

Equipped creature gets +1/+0.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Veteran Swordsmith

Other Soldier creatures you control get +1/+0.

Sunspear Shikari

As long as Sunspear Shikari is equipped, it has first strike and lifelink.

Adventuring Gear

Landfall — Whenever a land you control enters, equipped creature gets +2/+2 until end of turn.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Bonesplitter

Plains

Evolving Wilds

{T}, Sacrifice Evolving Wilds: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Kitesail Apprentice

As long as Kitesail Apprentice is equipped, it gets +1/+1 and has flying.

Leonin Den-Guard

As long as Leonin Den-Guard is equipped, it gets +1/+1 and has vigilance.

Unified Strike

Exile target attacking creature if its power is less than or equal to the number of Soldiers on the battlefield.