Value "cap" on blessed weapons?

[Dinji_Jinto]

I've come to own a lot of short skull swords and flaming swords, and I decided that I'd keep them to bless and sell to NPCs for a sort of income. I ran into a sort of problem, not a clue if it's intentional. As most people might know, blessing weapons increases their plat value. However, the value seems to drop at a certain point, depending on the weapon. I don't really see any reason behind this. If I put time into blessing something, the value shouldn't go down.

For a short skull sword, these are the rough plat values with each blessing level.

+0) 1 plat
+1) 4 plat
+2) 38 plat
+3) 129 plat
+4) 307 plat
+5) 599 plat
+6) 1036 plat
+7) 716 plat
+8) 761 plat
+9) 810 plat
+10) ?
+11) ?

I don't have the ability to bless +7 Aengus yet, but the value will almost certainly drop, as they are all the same for all god blessings. The values +7 to +9 were from when I was a Gov follower. I just don't understand the reasoning behind it. I feel like this should be changed somehow.

The same thing kind of goes for flaming swords.

+0) 5 plat
+1) 17 plat
+2) 158 plat
+3) 466 plat
+4) 1105 plat
+5) 746 plat
+6) 820 plat
+7) ?
+8) ?
+9) ?
+10) ?
+11) ?