i need to have a very precise information about these two abilities, because i need to spend 200 ed on a weapon change deed

these infos are taken from UOGUIDE.COM and i need a confirmation that it works like this even in this shard:
Crushing Blow: cost 20 Mana, increases the caster's damage by 50%
Double Strike: cost 30 Mana, allows an attacker to strike their opponent twice in the next single round of combat, There is a -10% damage penalty for this special move
To me, if the abilities are coded like this, it's a no brainer, double strike wins without a doubt:
if you can max your swing time and can continuosly chain the special move with mana leech we have:
Crushing Blow : 150% Damage + magic hit for weapon (harm,fireball,lightn,magicArrow) every 1.25 SEC
Double Strike: 90% Damage + magic hit for weapon (harm,fireball,lightn,magicArrow) every 0.625 SEC
Let's imagine a scenario where hit damage is 100 average and magic damage is 50 average over a span of 1 minute:
Crushing blow: 150+50 * 48 (swings in one minute) = 9600 Damage
Double Strike: 90 + 50 * 96 (swings in one minute) = 13440 Damage (+3840 damage)
if we have a higher magic damage for example 80 we have :
Crushing blow: 150+80 * 48 (swings in one minute) = 11040 Damage
Double Strike: 90 + 80 * 96 (swings in one minute) = 16320 Damage (+5280 damage)
Obviously the mana cost is higher (calculation made with Mana cost decrease 40% - cap):
Crushing Blow: 12 --> (x2) 24 (spam ability malus cost)
Double Strike: 18 --> (x2) 36 (spam ability malus cost)
Can someone answer this?
Or tell me if there are some fallacies in my formula?
Thanks in advance!!!