The very presence of a weapon provokes a man to use it.

[αὐτὸς γὰρ ἐφέλκεται ἄνδρα σίδηρος.]

Homer (fl. 7th-8th C. BC) Greek author

The Odyssey [Ὀδύσσεια], Book 16, l. 294 (16.294) [Odysseus] (c. 700 BC) [tr. Rieu (1946)]
    (Source)

(Greek (Source)), repeated in 19.13.

In Book 16, Odysseus offers this as part of the argument Telemachus can use to the suitors to explain why he has stripped the hall of weapons -- that, should the weapons remain, they might tempt drunken people to violence. Book 19, back at the hall, Odysseus repeats almost the same instructions to Telemachus. The same Greek is used for this phrase in both passages; some translators use the same language, others make changes to it.

Epigram (and title inspiration) in Joe Abercrombie's The Blade Itself (2006) -- "The blade itself incites to deeds of violence." Abercrombie was a fan of the Rome: Total War game, which included in its load pages the translation, "The blade itself incites to violence.

BOOK 16, l. 294

• "Steel itself, ready, draws a man to blows." [tr. Chapman (1616)]
• "One drawn sword draws another." [tr. Hobbes (1675), l. 276]
• "Oft ready swords in luckless hour incite / The hand of wrath, and arm it for the fight." [tr. Pope (1725)]
• "For the view / Itself of arms incites to their abuse." [tr. Cowper (1792), l. 348]
• "Steel itself oft lures a man to fight." [tr. Worsley (1861), st. 37]
• "Steel itself wooes men to battle!" [tr. Bigge-Wither (1869)]
• "For the steel blade itself lures men to blood." [tr. Musgrave (1869), l. 462]
• "For iron of itself draws a man thereto." [tr. Butcher/Lang (1879)]
• "For this is said aright, / That e'en of himself the iron draws on a man to smite." [tr. Morris (1887)]
• "Steel itself draws men on." [tr. Palmer (1891)]
• "For the sight of arms sometimes tempts people to use them." [tr. Butler (1898)]
• "For of itself does the iron draw a man to it." [tr. Murray (1919)]
• "Iron of itself tempts man's frailty." [tr. Lawrence (1932)]
• "Tempered iron can magnetize a man." [tr. Fitzgerald (1961)]
• "Iron all of itself works on a man and attracts him." [tr. Lattimore (1965)]
• "For iron of itself can tempt a man." [tr. Mandelbaum (1990)]
• "Iron has powers to draw a man to ruin." [tr. Fagles (1996)]
• "There's a force in iron that lures men on." [tr. D. C. H. Rieu (2002)]
• "For iron itself draws a man to employ it." [tr. Merrill (2002)]
• "Iron of itself draws a man on." [tr. Verity (2016)]
• "Weapons themselves can tempt a man to fight." [tr. Wilson (2017)]
• "For iron of itself attracts a man." [tr. Green (2018)]
• "Iron attracts a man all on its own." [tr. Johnston (2019)]
• "And beckoning, the iron itself drags the man." [Source]

BOOK 19, l. 13 -- items in italics are the same as their Book 16 counterparts.

• "As loadstones draw the steel, so steel draws man." [tr. Chapman (1616)]
• "One drawn sword draws another." [tr. Hobbes (1675)]
• "By sight of swords to fury fired." [tr. Pope (1725)]
• "For the view / Itself of arms incites to their abuse." [tr. Cowper (1792)]
• "Steel itself oft lures a man to fight." [tr. Worsley (1861), st. 2]
• "The sight of iron tempts to use it!" [tr. Bigge-Wither (1869)]
• "For the steel blade itself / Lures men to blood." [tr. Musgrave (1869)]
• "For iron of itself draws a man thereto." [tr. Butcher/Lang (1879)]
• "For e'en of himself the Iron to battle draweth men." [tr. Morris (1887)]
• "Steel itself draws men on." [tr. Palmer (1891)]
• "For the sight of arms sometimes tempts people to use them." [tr. Butler (1898)]
• "For of itself does the iron draw a man towards it." [tr. Murray (1919)]
• "Iron has that attraction for men." [tr. Lawrence (1932)]
• "The very presence of a weapon provokes a man to use it." [tr. Rieu (1946)]
• "Iron itself can draw men's hands." [tr. Fitzgerald (1961)]
• "Iron all of itself works on a man and attracts him." [tr. Lattimore (1965)]
• "For iron of itself can tempt a man." [tr. Mandelbaum (1990)]
• "Iron has powers to draw a man to ruin." [tr. Fagles (1996)]
• "Steel has a way of drawing a man to it." [tr. Lombardo (2000)]
• "There's a force in iron that lures men on." [tr. D. C. H. Rieu (2002)]
• "For iron itself draws a man to employ it." [tr. Merrill (2002)]
• "For iron of itself draws a man on." [tr. Verity (2016)]
• "For iron of itself attracts a man." [tr. Green (2018)]
• "For iron by itself / can draw a man to use it." [tr. Johnston (2019)]