The Tavern

We have a brand which gives HP on hit but we do not have a brand which gives MP on hit.
+3 "Mana leech" lajatang, fragile, damage is equal to plain +3 lajatang, gives 1d4 MP on hit.

Vampire's Tooth already has the niche of "completely useless unrandart weapon" covered

Would removing fragile make it useful? I was afraid it would be too powerful (giving more MP than staff of energy, does not require training Evo, potentially in 0.7 turn instead of 1.0 and also attacks enemy)

MP leeched should depend on damage done to avoid bag-of-rats syndrome.
And i think the weapon in question (it it must be a weapon; i think an amulet or a ring could work better) should have some other properties that would make it worthwhile for a spell-focused character to use (and preferably not only when low on mana). Out of the standart brands, protection and electrocution give non-melee specialised dudes reason to use them.

The idea is to have a randart which can make life of casters more enjoyable: less retreating, less luring.

Very good for heavily armoured spirit shielded melee. The only downside would be the lack of damage brand and lowish enchantment level.

Give it both mana drain and guardian spirit, call it "the <foo> of the vine stalker"

Laja of vines.

Be kinda cool to have an unrandart Magebane that's an antimagic axe that also heals your MP but has -cast

Just let Leech do mana vamp as well as regular vamp. Right now it's not too different from a regular vamp demon blade except for the increased proc chance.

Which made it very different from any other vamp weapon