For all those that don't know: Molten Armor now causes 170 Fire damage when hit for all ranks (Up from 75/130/170) and also increases your critical strike rating by 25% of your spirit.

Also the glyph has been changed to 15% spirit.

Currently on live my spirit unbuffed is 366

Unglyphed

(366/100)*25 = 91.5

91.5/45.91 = 1.99% crit chance

Glyphed

(366/100)*40 = 146.4

146.4/45.91 = 3.19% crit chance

Also I think this means that the optimal FFB or Fire gear will contain a fair bit of spirit.

(Post below shows what I thought before I did the calculations)

Edit: Changed calculations due to my L2read skills. It's late so be kind :D