I think, this has been mentioned somewhere before...
For some unknown reasons component #5900 sets the enchantment level (itm offset 0x60) of masterwork weapons (created by Item revisions) from '0' back to '1'.
Lolfixer component #8 detects this and therefore 'fixes' the item by setting the item flag 'Magical'. And so we are back to a magical +1 weapon...
One could argue about Lolfixer doing this but OTOH, what is the reason behind setting the enchantment level by SCS?
Edit:
I think, the changes happen in this section of bg1fix.tpa:
//////////////////////////////////////////////////////////////////////////////////////////////////////////
// correctly flag Enchantment level of certain items
//////////////////////////////////////////////////////////////////////////////////////////////////////////
LAF edit_item INT_VAR tv=1 STR_VAR item=~arow02 ax1h02 ax1h07 blun03 blun05 blun07 bolt02
dagg02 dart02 halb02 hamm02 staf02 sw1h02 sw1h05
sw1h08 sw1h14 sw1h22 sw1h24 sw1h98 sw2h02~
editstring=~enchantmentGT=>1~
END
IMHO it should only be executed if GAME_IS ~bg1 totsc~. If I look into a plain BGT game (BG2 fixpack installed) all enchantment levels are already fixed (but don't know about Tutu).
Maybe better would be a check inside the function, only setting an enchantment level if the flag 'Magical' is set.