Enormous Energy Blade

A +4/+0 swing for a two-mana equip is well ahead of the rate a cheap sword usually offers, and the tap clause is where that discount gets paid back. The attach trigger fires unconditionally: whatever creature the blade lands on gets tapped the moment it becomes equipped, whether that creature just resolved onto the battlefield or was already sitting untapped and ready to swing. So the boost never converts into damage on the turn you commit to it. You suit up now and attack next turn, always. Since equip is sorcery-speed by rule, there is no instant-speed window to exploit anyway: no ambush block, no surprise attacker to spring, no way to slap the blade on mid-combat and cash in. The whole sequence is telegraphed a full turn out, and the forced tap ensures even a board you already control cannot use the bonus immediately. That timing tax is the counterweight to the low, repeatable equip cost, and it points the card squarely at aggressive artifact builds that want cheap, reusable power and can afford to plan a beat ahead. It also cuts against holding a creature back on defense: whatever carries the blade is tapped down the instant it equips, committed rather than kept in reserve, unable to block until it untaps.