Increasing difficulty with heirlooming

[OoberNoob]

Hey guys, Ive been out for a while and decided to check and see how things were going here and I noticed I could reheirloom my items.  I was happy with what I had originally so I started heirlooming everything back to the way it was when I noticed that the difficulty was rising with each heirloom.  Luckily I noticed right before I heirloomed my bec for the third time because that would have made the difficulty higher than my strength, 18/18, which leaves heirlooming some of my favorite gear out of the question.   
Is there an updated list I can go by to check the stats of heirloomed equipment to ensure I dont raise the difficulty too high?

[Dravic]

I think that difficulty is NOT raised with heirlooms anymore.

[okiN]

I thought increased requirements with heirlooming were removed ages ago. Mine certainly haven't been changed.

[OoberNoob]

On a regular bec the difficulty is shown as 15 but on a tempered bec, at least on my profile, it shows the difficulty as 18.

[Lennu]

On a regular bec the difficulty is shown as 15 but on a tempered bec, at least on my profile, it shows the difficulty as 18.

There must be some mistake, diff going up from 15 to 18 is just ridiculous.

[WaltF4]

On a regular bec the difficulty is shown as 15 but on a tempered bec, at least on my profile, it shows the difficulty as 18.

Tempered is the outdated second tier heirloom modifier for polearms. My long awlpike also became tempered at the second tier of heirlooming and no longer showed up in game. It reappeared when I spent an additional heirloom point to make it masterwork. I do not know if this has been corrected as it occurred several days and 2 updates ago.

[OoberNoob]

Ok thanks for the imput 

Edit: Now that its masterwork it went back to 15, thanks for the help guys I was really panicking for a bit there