There was a time when the foruns recomended opinion was that you should not waste the practices on that spell.
That only changed after Viri making a comment and the code become more known.
"There are two purposes to bless arms, neither of which would do anything for "bless armor"."
This is blessed weapon.
Object 'Weapon' is type weapon, material ?????.
Extra flags: invis magic bless noremove.
Weight is 10, value is 6, level is 43.
Weapon type is ???.
Damage is ?d? (average ??).
This is a blessed armor.
Object '?????' is type armor, material ????.
Extra flags: glow hum magic bless nonmetal.
Weight is 20, value is 6, level is 31.
Armor class is 11 pierce, 11 bash, 11 slash, and 9 vs. magic.
Affects dex by -2.
Same flag. That is the point, expand it so that it works with armor also.
Does not has to be the same spell.