I get the issues with this being a 2 mana on outset. Northshire into Extra Arms feels bad. BUT, why not bump EA to 3 mana and keep 'More Arms!' at 2? Not like that couldn't be done. Similar approach could be taken to fix Twinspell but in the opposite direction. Initial iteration costs X, while the Twinspelled version costs X+1.
I get the issues with this being a 2 mana on outset. Northshire into Extra Arms feels bad. BUT, why not bump EA to 3 mana and keep 'More Arms!' at 2? Not like that couldn't be done. Similar approach could be taken to fix Twinspell but in the opposite direction. Initial iteration costs X, while the Twinspelled version costs X+1.