Blessant vs Bless

[OGRE]

More than just a translation query, but one for the Linguists.

As an English speaker, I have grown up reading and hearing the word "Bless", which according to online dictionary has meaning such as:

1. to consecrate or sanctify by a religious rite; make or pronounce holy.
2. to request of God the bestowal of divine favor on: Bless this house.
3. to bestow good of any kind upon:

Now that I listen to French, I occasionally come across Blessant, which phonetically is very similar to the English Bless. Blessant is translated as "to hurt" or "hurtful", which is sort of just the opposite of Bless.

Two phonetically equal sounds with opposite meanings. It's hard enough learning French in general, but when I gotta reverse the meaning in my head....oh it hurts so.

My question for the Linguists: It would seem these two words have a common pedigree. Why the divergent meaning?